Most Important MCQ Questions for Class 10 Science with Solutions for 2020 Board Exam

MCQ Questions for Class 10 Science Pdf: Science subjects which include Physics, Chemistry and Biology are very important for students who want to score good marks in their CBSE board examination. Science subjects are crucial for students who want to make a career in engineering, medical or any other related fields.

MCQ Questions for Class 10 Science Pdf Download 2020 Board Exam

Practicing Science MCQ for Class 10 CBSE is one of the best ways to prepare for CBSE class 10 board exam. There is no substitute for consistent practice whether one wants to understand a concept thoroughly or one wants to score better. By practicing more Science MCQ for Class 10 CBSE with answers, students can improve their speed and accuracy which can help them during their board exam.

CBSE Class 10 Science Marking Scheme

Section Type of Questions Marks
A: Question no. 1-14 Objective Type Questions (1 mark each) 20
A: Question no. 15-24 Short Answer Type Questions (3 marks each) 30
A: Question no. 25-30 Long Answer Type Questions (5 marks each) 30
  Total 80

CBSE Sample Papers for Class 10

MCQ Questions for Class 10 Science Pdf Chapter 1 Chemical Reactions and Equations

Question 1.
When crystals of lead nitrate are heated strongly in a dry test tube
(a) crystals immediately melt
(b) a brown residue is left
(c) white fumes appear in the test tube
(d) a yellow residue is left

Answer/ Explanation

Answer:
(b)Pungent smelling, brown fumes are evolved due to NO2 gas and brown coloured residue of lead oxide (PbO) is left.

 


Question 2.
A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation? [NCERT Exemplar]
(a) KMnO4 is an oxidising agent, it oxidises FeSO4
(b) FeSO4 acts as an oxidising agent and oxidises KMnO4
(c) The colour disappears due to dilution, no reaction is involved
(d) KMnO4 is an unstable compound and decomposes in the presence of FeSO4 to a colourless compound

Answer/ Explanation

Answer:
(a)Potassium permanganate (KMnO4) in the presence of dil. H2SO4, i.e. in acidic medium, acts as a strong oxidising agent. In acidic medium, KMnO4 oxidises ferrous sulphate to ferric sulphate.

 


Question 3.
Dilute hydrochloric acid is added to granulated zinc taken in a test tube. The following observations are recorded. Point out the correct observation.
(a) The surface of metal becomes shining
(b) The reaction mixture turns milky
(c) Odour of a pungent smelling gas is recorded
(d) A colourless and odourless gas is evolved

Answer/ Explanation

Answer:
(d)Zinc metal reacts with dil. HCl to form zinc chloride and bubbles of colourless and odourless hydrogen gas is evolved.

 


Question 4.
When a magnesium ribbon is burnt in air, the ash formed is
(a) black
(b) white
(c) yellow
(d) pink

Answer/ Explanation

Answer:
(b)When a Mg ribbon is burnt in air, the ash formed is of magnesium oxide which is white in colour.
2Mg(r) + O2(g) → 2MgO(f)

 


Question 5.
Three beakers labelled as A, B and C each containing 25 mL of water were taken. A small amount of NaOH, anhyd. CuSO4 and NaCl were added to the beakers A, B and C, respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers A and B whereas, in case of beaker C, the temperature of the solution falls. Which one of the following statements is/are correct?
I. In beakers A and B, exothermic process has occurred.
II. In beakers A and B, endothermic process has occurred.
III. In beaker C, the exothermic process has occurred.
IV. In beaker C, endothermic process has occurred. [NCERT Exemplar]
(a) Only I
(b) Only II
(c) I and IV
(d) II and III

Answer/ Explanation

Answer:
(c)As in case of beakers A and B, heat is given out, so temperature became high, hence it is an exothermic reaction while in beaker C, heat is absorbed from water, so temperature falls, hence it is an endothermic process.

 


Question 6.
Which of the following will be required to identify the gas evolved when dilute hydrochloric acid reacts with zinc metal?
(a) Red litmus paper
(b) pH paper
(c) Lime water
(d) A burning splinter

Answer/ Explanation

Answer:
(d)On reacting with dil. HCl, zinc metal forms zinc chloride and hydrogen gas is evolved. Presence of hydrogen gas can be checked by a burning splinter because H4 gas burnt in a splinter with a pop sound.

 


Question 7.
On immersing an iron nail in CuSO4 solution for few minutes, you will observe that
(a) no reaction takes place
(b) the colour of solution fades away
(c) the surface of iron nails acquire a black coating
(d) the colour of solution changes to green

Answer/ Explanation

Answer:
(b)Fe(s) + CuSO4 (aq) → FeSO4 (aq) + Cu(s)
Fe is present above in the reactivity series of metals. Hence, Fe displaces Cu from CuSO4 solution. And the colour of the solution fades away. This is an example of displacement reaction.

 


Question 8.
What happens when ferrous sulphate crystals are heated? [CCE 2014]
(a) A gas having the smell of burning sulphur is evolved
(b) No gas is evolved
(c) Brown coloured gas is evolved
(d) Colourless and odourless gas is evolved

Answer/ Explanation

Answer:
(a)The green colour of ferrous sulphate crystals changes to brownish black ferric oxide and smell of burning sulphur is evolved due to SO2 and SO3.

 


Question 9.
The colour of the precipitate formed when barium chloride solution is mixed with sodium sulphate solution is [CCE 2014]
(a) blue
(b) black
(c) white
(d) green

Answer/ Explanation

Answer:
(c)This is an example of a double displacement reaction and a white precipitate of barium sulphate is formed.

 


Question 10.
How the colour changes when the gases after thermal decomposition of ferrous sulphate come in contact with an acidified solution of potassium dichromate?
(a) Green to orange
(b) Red to colorless
(c) Orange to green
(d) Blue to green

Answer/ Explanation

Answer:
(c) The color changes from orange to green due to the formation of iron (III) sulphate

 


You can Also Check:

2020 Board Exam: Download CBSE Sample Papers for Class 10 Bundle PDF

CBSE Sample Papers for Class 10 Maths CBSE Sample Papers for Class 10 Standard
CBSE Sample Papers for Class 10 English CBSE Sample Papers for Class 10 Sanskrit
CBSE Sample Papers for Class 10 Social Science Formula Handbook for Class 10 Maths and Science
Class Name Subject – Maths Subject – Science
Class 10 NCERT Solutions for Class 10 Maths NCERT Solutions for Class 10 Science

MCQ Questions for Class 10 Science Pdf Chapter 2 Acids, Bases and Salts

Question 1
A solution turns red litmus blue, its pH is likely to be
(a) 1
(b) 4
(c) 5
(d) 10

Answer/ Explanation

Answer:
(d) 10

 


Question 2
A solution reacts with crushed-egg shells to give a gas that turns lime water milky. The solution contains
(a) NaCl
(b) HCl
(c) LiCl
(d) KCl

Answer/ Explanation

Answer:
(b) HCl

 


Question 3
10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HC1. If we take 20 mL of the same solution of NaOH, the amount of HC1 solution (the same solution as before) required to neutralise it will be
(a) 4 mL
(b) 8 mL
(c) 12 mL
(d) 16 mL

Answer/ Explanation

Answer:
(d) 16 mL

 


Question 4
Which one of the following types of medicines is used for treating indigestion?
(a) Antibiotic
(b) Analgesic
(c) Antacid
(d) Antiseptic

Answer/ Explanation

Answer:
(c) Antacid

 


Question 5
Write word equations and then balanced equations for the reaction taking place when
(a) dilute sulphuric acid reacts with zinc granules
(b) dilute hydrochloric acid reacts with magnesium ribbon
(c) dilute sulphuric acid reacts with aluminium powder
(d) dilute hydrochloric acid reacts with iron filing

Answer/ Explanation

Answer:
(a) Zinc + dilute sulphuric acid → Zinc sulphate + Hydrogen
Zn (s) + H2SO4 (aq) → ZnSO4 (aq) + H2 (g)

(b) Magnesium ribbon + dil. Hydrochloric acid → Magnesium chloride + Hydrogen
Mg (s) + 2 HCl (aq) → MgCl2 (aq) + H2 (g)

(c) Aluminium powder + dil. Sulphuric acid > Aluminium sulphate + Hydrogen
2Al (s) + 3H2SO4 (aq) → Al2 (SO4)3 (aq) + 3H2 (g)

(d) Iron filings + Dilute hydrochloric acid > Ferric chloride + Hydrogen
2Fe (s) + 6HCl (aq) → 2FeCl3 (aq) + 3H2 (g)

 


 

MCQ Questions for Class 10 Science Chapter 3 Metals and Non-Metals

Metals and Nonmetals Class 10 Question 1.
Which of the following pairs will give displacement reactions ?
(a) NaCl solution and copper metal.
(b) MgCl2 solution and aluminium metal.
(c) FeSO4 solution and silver metal.
(d) AgNO3 solution and copper metal.

Answer/ Explanation

Answer:
(d) AgNO3 solution and copper metal.

 


Question 2.
Which of the following methods is suitable for preventing an iron frying pan from rusting ?
(a) Applying grease
(b) Applying paint.
(c) Applying a coating of zinc
(d) All the above.

Answer/ Explanation

Answer:
(c) Applying a coating of zinc.

 


Question 3.
An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be
(a) calcium
(b) carbon
(c) silicon
(d) iron

Answer/ Explanation

Answer:
(a) Calcium.

 


Question 4.
Food cans are coated with tin and not with zinc because
(a) zinc is costlier than tin
(b) zinc has a higher melting point than tin
(c) zinc is less reactive than tin
(d) zinc is more reactive than tin.

Answer/ Explanation

Answer:
(d) Zinc is more reactive than tin.

 


 

MCQ Questions for Class 10 Science Chapter 4 Carbon and Its Compounds

Question 1.
Buckminster fullerene is an allotropic form of [NCERT Exemplar]
(a) phosphorus
(b) sulphur
(c) carbon
(d) tin

Answer/ Explanation

Answer:
(c) Buckminster fullerene is an allotrope of carbon containing clusters of 60 carbon atoms joined together to form spherical molecules. Its formula isC60 (C-sixty). It is a dark solid at room temperature and as compared to another allotropic form of carbon (diamond and graphite), it is neither very hard nor soft.

 


Question 2.
The hetero atoms present in
CH3 – CH2 – O – CH2 – CH2Cl are [NCERT Exemplar]
(i) oxygen
(ii) carbon
(iii) hydrogen
(iv) chlorine
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)

Answer/ Explanation

Answer:
(d) Atoms other than C and H, if present in organic compound, are called heteroatoms.

 


Question 3.
In which of the following .compounds -OH is the functional group? [NCERT Exemplar]
(a) Butanone
(b) Butanol
(c) Butanoic
(d) Butanal

Answer/ Explanation

Answer:
(b) Butanol, CH3—CH2—CH2—CH2—OH
The general formula of alcohols is CnH2n+1— OH.
For butanol, n = 4. So, formula is
C4H9—OH or CH3—CH2—CH2—CH2—OH

 


Question 4.
The soap molecule has a [NCERT Exemplar]
(a) hydrophilic head and a hydrophobic tail
(b) hydrophobic head and a hydrophilic tail
(c) hydrophobic head and a hydrophobic tail
(d) hydrophilic head and a hydrophilic tail

Answer/ Explanation

Answer:
(a) A soap molecule is made up of two parts- a long hydrocarbon part and a short ionic part —COONa group. The long hydrocarbon chain is hydrophobic (water repelling) and ionic portion is hydrophilic (water attracting).
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-1

 


Question 5.
Structural formula of benzene is [NCERT Exemplar]
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-5

Answer/ Explanation

Answer:
(c) Benzene molecule contains alternate single and . double bonds. Its formula is C6H6. In structure (b) formula is C6H12. In structure (a) double bond is not at alternate position. In (d) formula is C6H8.

 


Question 6.
Which of the following is not a straight chain hydrocarbon? [NCERT Exemplar]
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-6

Answer/ Explanation

Answer:
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-6.1
chain hydrocarbon not straight chain hydrocarbon. Rest three are straight chain hydrocarbons.

 


Question 7.
Which among the following are unsaturated hydrocarbons? [NCERT Exemplar]
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-7
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (ii) and (iv)
(d) (iii) and (iv)

Answer/ Explanation

Answer:
(c) Unsaturated hydrocarbons have double or triple bond in the structure. Both (ii) and (iv) structures have triple and double carbon-carbon bonds respectively.

 


Question 8.
Chlorine reacts with saturated hydrocarbons at room temperature in the [NCERT Exemplar]
(a) absence of sunlight
(b) presence of sunlight
(c) presence of water
(d) presence of hydrochloric acid

Answer/ Explanation

Answer:
(b) Chlorine reacts with saturated hydrocarbon at room temperature in the presence of sunlight.
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-8

 


Question 9.
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-9
In the above given reaction, alk.KMnO4 acts as [NCERT Exemplar]
(a) reducing agent
(b) oxidising agent
(c) catalyst agent
(d) dehydrating

Answer/ Explanation

Answer:
(b) KMnO4 acts as oxidising agent, because it removes hydrogen from CH3CH2OH and adds one oxygen to it.

 


Question 10.
Butanone is a four carbon compound with functional group [NCERT Exemplar]
(a) carboxylic acid
(b) aldehyde
(c) ketone
(d) alcohol

Answer/ Explanation

Answer:
(c) In butanone, the functional group is
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-10

 


Question 11.
Identify the unsaturated compounds from the following [NCERT Exemplar]
(i) Propane
(ii) Propene
(iii) Propyne
(iv) Chloropropane
(a) (i) and (ii)
(b) (ii) and (iv)
(c) (iii) and (iv)
(d) (ii) and (iii)

Answer/ Explanation

Answer:
(d) Propene, CH3CH=CH2 (ii) and propyne, CH3— C = CH (iii) both have double and triple bonds, respectively, hence are unsaturated compounds.

 


Question 12.
Which of the following does not belong to the same homologous series? [NCERT Exemplar]
(a) CH4
(b) C2H6
(c) C3H8
(d) C4H8

Answer/ Explanation

Answer:
(d) Because succesive members of a homologous series differ by —CH2 unit.
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-12
Thus, C4H10 is the next member of this series. So, homologous series of alkanes is:
methane (CH4), ethane (C2H6), propane (C3H8) and butane (C4H10).
So, C4H8 does not belong to the homologous series.

 


Question 13.
Ethane with molecular formula C2H6 has [NCERT Exemplar]
(a) 6 covalent bonds
(b) 7 covalent bonds
(c) 8 covalent bonds
(d) 9 covalent bonds

Answer/ Explanation

Answer:
(b) Structure formula of ethane (C2H6) is
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-13
It is clear that it has 7 covalent bonds.

 


Question 14.
Which of the following are correct structural isomers of butane? [NCERT Exemplar]
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-14
(a) (i) and (iii)
(b) (ii) and (iv)
(c) (i) and (ii)
(d) (iii) and (iv)

Answer/ Explanation

Answer:
(a) Structure (i) is n-butane and structure (iii) is iso-butane. Since, molecular formula is same, only structures are different. So, (i) and (iii) are isomers while structures (ii) and (iv) have molecular formulaC4H8.

 


Question 15.
In the soap micelles, [NCERT Exemplar]
(a) the ionic end of soap is on the surface of the cluster while the carbon chain is in the interior of the cluster
(b) ionic end of soap is in the interior of the cluster and the carbon chain is out of the cluster
(c) Both ionic end and carbon chain are in the interior of the cluster
(d) Both ionic end and carbon chain are on the exterior of the cluster

Answer/ Explanation

Answer:
(a) A ‘spherical aggregate of soap molecules’ in the soap solution in water is called a ‘micelle’. In a soap micelle, the soap molecules are arranged readily with hydrocarbon ends directed towards the centre and ionic ends directed outwards.
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-15

 


Question 16.
Vinegar is a solution of [NCERT Exemplar]
(a) 50% – 60% acetic acid in alcohol
(b) 5% – 8% acetic acid in alcohol
(c) 5% – 8% acetic acid in water
(d) 50% – 60% acetic acid in water

Answer/ Explanation

Answer:
(c) A 5%-8% solution of acetic acid in water is called vinegar.

 


Question 17.
Oils on treating with hydrogen in the presence of palladium or nickel catalyst form fats. This is an example of [NCERT Exemplar]
(a) addition reaction
(b) substitution reaction
(c) displacement reaction
(d) oxidation reaction

Answer/ Explanation

Answer:
(a) Oils are unsaturated compounds containing double bonds. Addition reactions are characteristic property of unsaturated hydrocarbons. The given reaction is an example of addition reaction.

 


Question 18.
Carbon forms four covalent bonds by sharing its four valence electrons with four univalent atoms, e.g. hydrogen. After the formation of four bonds, carbon attains the electronic configuration of [NCERT Exemplar]
(a) helium
(b) neon
(c) argon
(d) krypton

Answer/ Explanation

Answer:
(b) Electronic configuration of carbon (C) = 2, 4 when it forms four covalent bonds by sharing its four valence electrons with hydrogen, it forms CH4 molecule like this
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-18
Now, electronic configuration of C in CH

4 = 2, 8.
Atomic number of Ne is 10. Its electronic K L configuration is 2,8. Therefore, after the formation of four bonds, carbon attains the electronic configuration of neon.

 


Question 19.
Mineral acids are stronger acids than carboxylic acids because
(i) mineral acids are completely ionised.
(ii) carboxylic acids are completely ionised.
(iii) mineral acids are partially ionised.
(iv) carboxylic acids are partially ionised.
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (ii)
(d) (iii) and (iv)

Answer/ Explanation

Answer:
(a) Mineral acids are strong acids which ionise almost completely and carboxylic acids are weak acids which ionise only pardally.

 


Question 20.
While cooking, if the bottom of the vessel is getting blackened on the outside, it means that [NCERT Exemplar]
(a) food is not cooked completely
(b) the fuel is not burning completely
(c) fuel is wet
(d) fuel is burning completely

Answer/ Explanation

Answer:
(b) The unburnt particles of the fuel present in smoke blacken the vessel from outside.

 


Question 21.
The reaction in which a reagent (partially or completely) replaces atom or group of atoms from saturated compounds or A are called B reaction.
Here, A and B respectively refers to
(a) unsaturated compounds, addition
(b) unsaturated compounds, substitution
(c) benzene, substitution
(d) alkene, addition

Answer/ Explanation

Answer:
(c) Substitution reaction is usually given by saturated compounds and benzene. Unsaturated compounds usually give addition reactions.

 


Question 22.
The table gives information about some esters and the fragrance they produce.

Ester Fragrance
Ethyl methanoate Rum
Methyl butanoate Apple
Ethyl butanoate Pineapple
Propyl ethanoate Pear

Which structure do the ester compounds in the table have in common?
ncert-solutions-for-class-10-science-chapter-4-carbon-and-its-compounds-22

Answer/ Explanation

Answer:
(d) All esters have the common structure of carboxylic group represented by the suffix date.

 


Question 23
Ethane, with the molecular formula C2Hhas
(a) 6 covalent bonds
(b) 7 covalent bonds
(c) 8 covalent bonds
(d) 9 covalent bonds

Answer/ Explanation

Answer:
(b) 7 covalent bonds.

 


Question 24
Butanone is a four-carbon compound with the functional group
(a) carboxylic acid
(b) aldehyde
(c) ketone
(d) alcohol

Answer/ Explanation

Answer:
(c) Ketone.

 


Question 25
While cooking, if the bottom of the vessel is getting blackened on the outside, it means that
(a) the food is not cooked completely.
(b) the fuel is not burning completely.
(c) the fuel is wet.
(d) the fuel is burning completely.

Answer/ Explanation

Answer:
(b) The fuel is not burning completely.

 


Question 26
Explain the nature of the covalent bond using the bond formation in CH3Cl.

Answer/ Explanation

Answer:
Covalent bond is formed by sharing of electrons so that the combining atoms complete their outermost shell.

In CH3Cl : C = 6, H = 1 and Cl = 17 And their electronic configuration is C – 2,4, H – 1 and Cl – 2, 8, 7
NCERT Solutions for Class 10 Science Chapter 4 Textbook Chapter End Questions Q4
Three hydrogen atoms complete their shells by sharing three electrons (one electron each) of carbon atom.
Chlorine completes its outer shell by sharing its one out of seven electrons with one electron of carbon atom.
Thus carbon atom shares all its four electrons with three hydrogen atoms and one of chlorine atom and completes its outermost shell and single covalent bonds are formed in CH3Cl.

 


Question 27
Draw the electron dot structures for
(a) ethanoic acid
(b) propanone
(c) H2S
(d) F2.

Answer/ Explanation

Answer:
NCERT Solutions for Class 10 Science Chapter 4 Textbook Chapter End Questions Q5

 


 

MCQ Questions for Class 10 Science Chapter 5 Periodic Classification of Elements

Question 1
Which of the following statements is not a correct statement about the trends wlien going from left to right across the periods of Periodic Table.
(a) The elements become less metallic in nature.
(b) The number of valence electrons increases.
(c) The atoms lose their electrons more easily.
(d) The oxides become more acidic.

Answer/ Explanation

Answer:
(c) The atoms lose their .electrons more easily.

 


Question 2
Element X forms a chloride with the formula XCl2, which is solid with a high melting point. X would most likely to be in the same group of the periodic table as
(a) Na
(b) Mg
(c) Al
(d) Si

Answer/ Explanation

Answer:
(b) Mg

 


Question 3
Which element has
(a) two shells, both of which are completely filled with electrons ?
(b) the electronic configuration 2, 8, 2 ?
(c) a total of three shells, with four electrons in its valence shell ?
(d) a total of two shells with three electrons in its valence shell. v
(e) twice as many electrons in its second shell as in its first shell ?

Answer/ Explanation

Answer:
(a) Neon (2, 8)
(b) Magnesium
(c) Silicon (2, 8, 4)
(d) Boron (2, 3)
(e) Carbon (2, 4)

 


Question 4
(a) What property do all elements in the same column of the Periodic Table as boron have in common ?
(b) What property do all elements in the same column of the Periodic Table . as fluorine have in common ?

Answer/ Explanation

Answer:
(a) Elements in the same column or group as boron have valency of three and have three valence electrons.
(b) Elements in the same column or group as fluorine form acidic oxides and have seven electrons in their outermost shells and have valency of one.

 


Question 5
An atom has electronic configuration 2, 8, 7.
(a) What is the atomic number of this element ?
(b) To which of the following elements would it be chemically similar ? (Atomic numbers are given in parentheses.)
N (7), F (9), P (15), Ar (18)

Answer/ Explanation

Answer:
(a) The atomic number of the given element is 2 + 8 + 7(= 17).
(b) It would be chemically similar to fluorine [F(9)] because its electronic configuration is 2, 7.

 


 

MCQ Questions for Class 10 Science Chapter 6 Life Processes

Question 1.
Yeast respires anaerobically using sugar as a substrate. Out of the options given below, choose the correct combination of condition and product?

Condition Product
(a) Aerobic Alcohol
(b) Aerobic Lactic acid
(c) Anaerobic Alcohol
(d) Anaerobic Lactic acid
Answer/ Explanation

Answer:
(c) Under an aerobic condition, yeast respires and converts glucose to alcohol and CO2.

 


Question 2.
The table shows the percentage composition of four samples of air. Which sample could have been breathed out by a person after vigorous exercise?

Samples Oxygen Carbondioxide Water Vapour
(a) 16 0.3 Saturated
(b) 16 4 Saturated
(c) 21 0.03 Trace
(d) 21 3 Trace
Answer/ Explanation

Answer:
(b) This is because rapid aerobic respiration occurs – during vigorous exercise in order to obtain more energy.

 


Question 3.
Cramps caused during sudden activities are due to the formation of
(a) lactic acid
(b) acetic acid
(c) excess of water
(d) ethanol

Answer/ Explanation

Answer:
(a) Lactic acid is formed by the breakdown of pyruvate when oxygen is insufficient in muscles instead of forming C02 and water. Accumulation of excess lactic acid in the muscles causes cramps.

 


Question 4.
Which of the following plays nose like function in plants?
(a) Flower
(b) Phloem
(c) Stomata
(d) Chlorophyll

Answer/ Explanation

Answer:
(c) Stomata are pores which help in the passage of air in the plants.

 


Question 5.
Which changes occur when a person breathe in deeply?

Diaphragm Muscle External Intercostal Muscles
(a) Contracts Contract
(b) Contracts No change
(c) Relaxes Contract
(d) Relaxes Relax
Answer/ Explanation

Answer:
(a) When a person breathes deeply the external intercostal muscles contract causing the rib cage to swing up and out. Also, the diaphragm contracts and flattens causing the thoracic cavity to increase in volume and decrease in pressure.

 


Question 6.
ncert-solutions-for-class-10-science-chapter-6-life-processes-6
The diagram given above shows part of the lining of the human trachea. What is the function of X?
(a) Gaseous exchange
(b) Mucus removal
(c) Phagocytosis
(d) Secretion of mucus

Answer/ Explanation

Answer:
(b) The cilia (X) of the cells lining the air passages move in a sweeping motion to keep the air passages clean. The constant action of these cilia carry mucus and debris upward into the pharynx where they are swallowed.

 


Question 7.
The table given below shows the percentage composition of a gas in inspired and in expired air.

%Composition
Inspired Air Expired Air
21.0 16.0

What is the gas?
(a) Carbon dioxide
(b) Nitrogen
(c) Oxygen
(d) Water vapour

Answer/ Explanation

Answer:
(c) The gas is oxygen as atmospheric air has approximately 21% of oxygen

 


Question 8
The kidneys in human beings are a part of the system for
(i) nutrition
(ii) respiration
(iii) excretion
(iv) transportation

Answer/ Explanation

Answer:
(iii) Excretion

 


Question 9
The xylem in plants are responsible for
(i) transport of water
(ii) transport of food
(iii) transport of amino acids
(iv) transport of oxygen

Answer/ Explanation

Answer:
(i) Transport of water

 


Question 10
The autotrophic mode of nutrition requires
(i) carbon dioxide and water
(ii) chlorophyll
(iii) sunlight
(iv) all of the above

Answer/ Explanation

Answer:
(iv) All of the above

 


Question 11
The breakdown of pyruvate to give carbon dioxide, water and energy takes place in
(i) cytoplasm
(ii) mitochondria
(iii) chloroplast
(iv) nucleus

Answer/ Explanation

Answer:
(ii) Mitochondria

 


 

MCQ Questions for Class 10 Science Chapter 7 Control and Coordination

Question 1
Which of the following is a plant hormone?
(a) Insulin
(b) Thyroxin
(c) Oestrogen
(d) Cytokinin

Answer/ Explanation

Answer:
(d) Cytokinin

 


Question 2
The gap between two neurons is called a
(a) dendrite
(b) synapse
(c) axon
(d) impulse

Answer/ Explanation

Answer:
(b) Synapse

 


Question 3
The brain is responsible for
(a) thinking
(b) regulating the heart beat
(c) balancing the body
(d) all of the above

Answer/ Explanation

Answer:
(b) All of the above

 


 

MCQ Questions for Class 10 Science Chapter 8 How do Organisms Reproduce

Question 1.
Asexual reproduction takes place through budding in [NCERT]
(a) Amoeba
(b) Yeast
(c) Plasmodium
(d) Leishmania

Answer/ Explanation

Answer:
(b) Asexual reproduction in Hydra and yeast takes place by budding.

 


Question 2.
The ability of a cell to divide into several cells during reproduction in Plasmodium is called [NCERT Exemplar]
(a) budding
(b) reduction division
(c) binary fission
(d) multiple fission

Answer/ Explanation

Answer:
(d) Multiple fission Organisms divide into many daughter cells simultaneously, e.g. Plasmodium.

 


Question 3.
The anther contains [NCERT]
(a) sepals
(b) ovules
(c) carpels
(d) pollen grains

Answer/ Explanation

Answer:
(d) Anther is the male reproductive part in plants. It contains pollen grains, having male germ cells.

 


Question 4.
Characters that are transmitted from parents to offspring during reproduction show [NCERT Exemplar]
(a) only similarities with parents
(b) only variations with parents
(c) both similarities and variations with parents
(d) neither similarities nor variations

Answer/ Explanation

Answer:
(c) In sexual reproduction, the offsprings are not exactly identical to the parents or to one another. This is because the offsprings receive some genes from mother and some from father. Because of mixing of genes on re-establishment of the exact number of chromosomes as in the parents, the offsprings show both similarities and variations with their parents.

 


Question 5.
Which among the following diseases is not sexually transmitted? [NCERT Exemplar]
(a) Syphilis
b) Hepatitis
(c) HIV-AIDS
(d) Gonorrhoea

Answer/ Explanation

Answer:
(b) The diseases, which are spread by sexual contact with an infected person are called Sexually Transmitted Diseases or STDs, e.g. gonorrhoea, syphilis and AIDS. Hepatitis is a water borne viral disease which affects liver.

 


Question 6.
Which of the following is not a part of the female reproductive system in human beings? [NCERT]
(a) Ovary
(b) Uterus
(c) Vas deferens
(d) Fallopian tube

Answer/ Explanation

Answer:
(c) Vas deferens is a part of male reproductive system in humans.

 


Question 7.
A feature of reproduction that is common to Amoeba, Spirogyra and yeast is that [NCERT Exemplar]
(a) they reproduce asexualiy
(b) they are all unicellular
(c) they reproduce only sexually
(d) they are all multicellular

Answer/ Explanation

Answer:
(a) Amoeba and yeast are unicellular while Spirogyra is multicellular. But, all the three reproduce asexualiy.

 


Question 8.
Which among the following statements are true for unisexual flowers? [NCERT Exemplar]
I. They possess both stamen and pistil.
II. They possess either stamen or pistil.
III. They exhibit cross-pollination.
IV. Unisexual flowers possessing only stamens cannot produce fruits.
(a) I and IV
(b) II, III and IV
(c) III and IV
(d) I, III and IV

Answer/ Explanation

Answer:
(b) The flowers which are unisexual (papaya, watermelon) contain either stamens or carpels. Since, only one reproductive organ is present in them, they depend on cross-pollination to form zygote after fertilisation. Both stamens and carpels are required for fertilisation, so only one of them cannot produce fruits.

 


Question 9.
Length of pollen tube depends on the distance between [NCERT Exemplar]
(a) pollen grain and upper surface of stigma.
(b) pollen grain on upper surface of stigma and ovule.
(c) pollen grain in anther and upper surface of stigma.
(d) upper surface of stigma and lower part of style.

Answer/ Explanation

Answer:
(b) Length of pollen tube depends on the distance between pollen grain on upper surface of stigma and ovule. A pollen grain falls on the stigma of the carpel, bursts open and develops a pollen tube downwards through the style towards the ovule in the ovary.

 


Question 10.
Which among the following statements arer true for sexual reproduction in flowering plants? [NCERT Exemplar]
I. It requires two types of gametes.
II. Fertilisation is a compulsory event.
III. It always results in formation of zygote.
IV. Offsprings formed are clones.
(a) I and IV
(b) I and II
(c) I, II and III
(d) I, II and IV

Answer/ Explanation

Answer:
(c) Sexual reproduction creates variation in organisms, so, clones cannot be produced through it. Clones are identical copy of parent organism. Sexual reproduction needs two type of gametes, i.e. male and female to form zygote after fertilisation.

 


Question 11.
Factors responsible for the rapid spread of bread mould on slices of bread are [NCERT Exemplar]
I. large number of spores.
II. availability of moisture and nutrients in bread.
III. presence of tubular branched hyphae.
IV formation of round-shaped sporangia
(a) I and III
(b) II and IV
(c) I and II
(d) III and IV

Answer/ Explanation

Answer:
(c) Under favourable Conditions (like damp and warm conditions, availability of nutrients), the fungal spores present in the air, lands on food, germinate and produce new plaints.

 


Question 12.
During adolescence various changes occur in the body of humans. Mark one change associated with sexual maturation in males. [NCERT Exemplar]
(a) Loss of milk teeth
(b) Increase in body height
(c) Cracking of voice
(d) Weight gain

Answer/ Explanation

Answer:
(c) Hypertrophy of larynx results in low pitched. cracking voice in human males during adolescence.

 


Question 13.
Observe the diagram given along side.
ncert-solutions-class-10th-science-chapter-8-organisms-reproduce-13
What happens after the above stage?
(a) The ovary splits open
(b) Ovary develops into a fruit and ovules into seeds
(c) The pvules are dispersed
(d) Germination of seeds takes place

Answer/ Explanation

Answer:
(b) Ovary develops into a fruit and ovulesdnto seeds as in the above given diagram fertilisation has already taken place.

 


Question 14.
What in your opinion could be the best reason to explain why menstruation is not taking place in a healthy woman?
(a) Early release of ovum
(b) Psychological reason
(c) Fertilisation of ovum
(d) Build up of female sex hormones in the blood stream

Answer/ Explanation

Answer:
(c) If a woman is not having her menstruation on time the probable reason from the given option is that fertilisation of ovum has taken place. Because, during gestation period of pregnancy, menstruation does not take place.

 


Question 15.
The correct sequence of reproductive stages seen in flowering plants is [NCERT Exemplar]
(a) gametes, zygote, embryo, seedling
(b) zygote, gametes, embryo, seedling
(c) seedling, embryo, zygote, gametes
(d) gametes, embryo, zygote, seedling

Answer/ Explanation

Answer:
(a) Correct sequence of reproductive stages in flowering plants is → formation of gametes → fusion of gametes to form zygote → zygote develops into embryo in the ovary → ovule develops a tough coat and converts into a seed.

 


Question 16.
Offsprings formed by asexual method of reproduction have greater similarity among themselves because [NCERT Exemplar]
I. asexual reproduction involves only one parent.
II. asexual reproduction does not involve gametes.
III. asexual reproduction occurs before sexual reproduction.
IV. asexual reproduction occurs after sexual reproduction.
(a) I and II
(b) I and III
(c) II and IV
(d) III and IV

Answer/ Explanation

Answer:
(a) Offsprings have greater similarity as only one parent is involved in asexual reproduction thus, no gametes are formed.

 


Question 17.
Two flowers are identified by a botanist with the following features that flower A is having only stamen and flower B is having both stamen and pistil. Which of the following statements is correct?
(a) Flower A will bear seeds and flower B cannot bear seeds after fertilisation.
(b) Flower A will produce pollen grains and flower B cannot produce pollen grains.
(c) Flower A cannot be fertilised and flower B can show fertilisation.
(d) Neither flower A and nor flower B can show self-pollination.

Answer/ Explanation

Answer:
Option (c) is correct. Since, flower A bears only stamen, i.e. male reproductive part so, it cannot get fertilised. And flower B bears both male and female reproductive parts, therefore it can get fertilised by pollination and can change into fruit.

 


Question 18
Asexual reproduction takes place through budding in
(a) amoeba
(b) yeast
(c) plasmodium
(d) leishmania

Answer/ Explanation

Answer:
(b) Yeast

 


Question 19
Which of the following is not a part of the female reproductive system in human beings ?
(a) Ovary
(b) Uterus
(c) Vas deferens
(d) Fallopian tube

Answer/ Explanation

Answer:
(c) Vas deferens

 


Question 20
The anther contains
(a) sepals
(b) ovules
(c) carpel
(d) pollen grains

Answer/ Explanation

Answer:
(d) Pollen grains

 


 

MCQ Questions for Class 10 Science Chapter 9 Heredity and Evolution

Question 1.
An example of homologous organs is [NCERT]
(a) our arm and a dog’s foreleg
(b) our teeth and an elephant’s tusks
(c) potato and runners of grass
(d) All of the above

Answer/ Explanation

Answer:
(a) Our arm and a dog’s foreleg is the example of homologous organs.

 


Question 2.
The science, which deals with study of heredity and variations is called
(a) phylogeny
(b) embryology
(c) genetics
(d) palaeontology

Answer/ Explanation

Answer:
(c) The genetics is the study of heredity and variations and includes their occurrence, causes, benefits, disadvantages, significance, etc.

 


Question 3.
Archaeopteryx is a connecting link between
(a) reptiles and aquatic animals
(b) birds and insects
(c) reptiles and birds
(d) birds and dinosaurs

Answer/ Explanation

Answer:
(c) Archaeopteryx is a connecting link- between the reptiles and birds. It appears like a bird, but has other features which are present in reptiles, e.g. it has wings like bird, but teeth and tail like the reptilians.

 


Question 4.
For palaeontological studies a scientist will gather the evidences from
(a) study of homology
(b) study of analogy
(c) fossils
(d) All of these

Answer/ Explanation

Answer:
(d) Study of homologous and analogous organs indicates the origin and modification in organisms and study of fossils indicates the age and features of an organism.

 


Question 5.
In evolutionary terms, we have more in common with [NCERT]
(a) a Chinese school boy
(b) a chimpanzee
(c) a spider
(d) a bacterium

Answer/ Explanation

Answer:
(a) Chinese school boy because both of us belong to the same species, i.e. Homo sapiens.

 


Question 6.
Aditya was observing some organisms in lab and tried to compare them. The presence of which organs will confirm to him that they share evolutionary history?
(a) Analogous organs
(b) Paralogous organs
(c) Homologous organs
(d) None of these

Answer/ Explanation

Answer:
(c) Homologous organs are present in organisms who share evolutionary history. However, these organs perform different functions in different organisms.

 


Question 7.
New species may be formed if
I. DNA undergoes significant changes in germ cells. .
II. chromosome number changes in the gamete.
III. there is no change in the genetic material.
IV. mating does not take place.
(a) I and II
(b) I and III
(c) II, III and IV
(d) I, II and III

Answer/ Explanation

Answer:
(a) New species may be formed if the DNA changes are severe enough, such as a change in the number of chromosome. This leads to new variations.

 


Question 8.
Which of the following statements is not true with respect to variation?
(a) All variations in a species have equal chance of survival.
(b) Change in genetic composition results in variation.
(c) Selection of variants by environmental factors forms the basis of evolutionary processes.
(d) Variation is minimum in asexual reproduction.

Answer/ Explanation

Answer:
(a) All variations in a species do not have equal chances of survival. Some of the variations may be so drastic that the new DNA copy cannot work with the cellular apparatus it inherits. Such, a newborn cell dies soon.

 


Question 9.
Select the statement that describes characteristics of genes. .
(a) Genes are specific sequence of bases in a DNA molecule.
(b) A gene does not code for proteins.
(c) In individuals of a given species, a specific gene is located on a particular chromosome.
(d) Each chromosome has only one gene.

Answer/ Explanation

Answer:
(b) Genes are stretches of DNA found on chromosomes of a cell. A gene contains information for making proteins in a cell. A specific gene is located on a particular chromosome in individuals of a given species.

 


Question 10.
If a round, green seeded pea plant (RRyy) is crossed with wrinkled, yellow seeded pea plant (rrYY), the seeds produced in F1 – generation will be [NCERT Exemplar]
(a) round and yellow
(b) round and green
(c) wrinkled and green
(d) wrinkled and yellow

Answer/ Explanation

Answer:
(a) The cross between RRyy and rrYY seeds will produce RrYy (round and yellow) seeds in F1-generation, because round and yellow are the dominant traits.

 


Question 11.
From the list given below, select the character, which can be acquired but not inherited. [NCERT Exemplar]
(a) colour of eye
(b) colour of skin
(c) size of body
(d) nature of hair

Answer/ Explanation

Answer:
(c) Acquired traits develop in response to the environment. The size of the body is an acquired trait because it can vary based on the availability of less or more food. The other three colour of eye and skin and nature of hair are characters inherited from the parents.

 


Question 12.
According to the evolutionary theory, formation of a new species is generally due to [NCERT Exemplar]
(a) sudden creation by nature.
(b) accumulation of variations over several generations.
(c) clones formed during asexual reproduction.
(d) movement of individuals from one habitat to another

Answer/ Explanation

Answer:
(b) Accumulation of variations over several generations forms new species. Genetic drift accumulates different changes in sub-populations of a species. Also, natural selection may also operate differendy in the different geographic locations. Eventually, different groups of new species will be formed.

 


Question 13.
Select the incorrect statement. [NCERT Exemplar]
(a) Frequency of certain genes in a population changes over several generations resulting in evolution.
(b) Reduction in weight of the organism due to starvation is genetically controlled.
(c) Low weight parents can have heavy weight progeny.
(d) Traits which are not inherited over generations do not cause evolution.

Answer/ Explanation

Answer:
(b) The weight reduction due to starvation will not change the DNA of the germ cells, because low weight is not a trait that is genetically controlled or inherited. Also, low weight parents may have heavy weight progeny.

 


Question 14.
In human males all the chromosomes are paired perfectly except one. This/these unpaired chromosome is/are
I. large chromosome
II. small chromosome
III. Y-chromosome IV X-chromosome
(a) I and II
(b) Only III
(c) III and IV
(d) II and IV

Answer/ Explanation

Answer:
(c) In human males, one pair called the sex chromosomes are unpaired. Here, one is a normal-sized X-chromosome while other is a short Y-chromosome. Women have a perfect pair of sex chromosomes, both called X.

 


Question 15.
Rajneesh was studying the fossils of two different types, fossil A was found in upper layer of Earth and B in deeper layers. What can be predicted regarding the age of these fossils?
(a) A has recently become extinct
(b) B has become extinct recently
(c) The time of extinction cannot be determined
(d) None of the above

Answer/ Explanation

Answer:
(a) Since, fossil A was found in upper layer of earth, it suggests that the organism has become extinct recently. Fossil B found in deeper layer must have become extinct long time ago and deposition of other layers occurred over it during this period.

 


Question 16.
A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic makeup of the tall parents can be depicted as [NCERT]
(a) TTWW
(b) TTww
(c) TtWW
(d) TtWw

Answer/ Explanation

Answer:
(c) Parent with genotype TtWW produce two types of gametes TW and tW, while the other with genotype ttww produce only one type of gamete W.
ncert-solutions-for-class-10th-science-chapter-9-heredity-and-evolution-16

 


 

MCQ Questions for Class 10 Science Chapter 10 Light, Reflection and Refraction

Question 1.
Hold a highly polished steel spoon curved inwards close to your face and move it slowly away from your face. What will you observe?
(a) Enlarged and erect image of your face
(b) Smaller and inverted image of your face
(c) Smaller and erect image of your face
(d) Enlarged and inverted image of your face

Answer/ Explanation

Answer:
(b) The inner curved surface of a highly polished steel spoon acts as a concave mirror. When the spoon is at a small distance from the face such that, the object lies between pole and focus of concave mirror, so an enlarged and erect image of your face will be observed but as the spoon is slowly moved away from the face, the image becomes smaller and appears inverted.

 


Question 2.
Which one of the following materials cannot be used to make a lens? [NCERT]
(a) Water
(b) Glass
(c) Plastic
(d) Clay

Answer/ Explanation

Answer:
(d) Clay can never be transparent, so it cannot be used to make lens.

 


Question 3.
No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be [NCERT]
(a) plane
(b) concave
(c) convex
(d) either plane or convex

Answer/ Explanation

Answer:
(d) Plane mirrors and convex mirrors always form the erect images.

 


Question 4.
The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object? [NCERT]
(a) Between principal focus and centre of curvature
(b) At centre of curvature
(c) Beyond centre of curvature
(d) Between pole of the mirror and its principal focus

Answer/ Explanation

Answer:
(d)

 


Question 5.
An object AB is placed in front of a convex lens at its centre of curvature as shown in figure below.
ncert-solutions-class-10th-science-chapter-10-light-reflection-refraction-5
Four students traced the path of light ray after refraction through the lens. Which one of them is correct?
ncert-solutions-class-10th-science-chapter-10-light-reflection-refraction-5.1
(a) Only I
(b) Only II
(c) Only III
(d) Only IV

Answer/ Explanation

Answer:
(d) When the object is placed at centre of curvature (2Fx) of convex lens, the same sized image is formed at 2F2. The image formed is real and inverted.

 


Question 6.
A spherical mirror and a thin spherical lens have each of a focal length -15 cm. The mirror and lens are likely to be [NCERT]
(a) both concave
(b) both convex
(c) mirror is concave and lens is convex
(d) mirror is convex and lens is concave

Answer/ Explanation

Answer:
(a) The focal length is taken as negative for both concave mirror and concave lens.

 


Question 7.
Which of the following can make a parallel beam of light when light from a point source is incident on it? [NCERT Exemplar]
(a) Concave mirror as well as convex lens
(b) Convex mirror as well as concave lens
(c) Two plane mirrors placed at 90° to each other
(d) Concave mirror as well as concave lens

Answer/ Explanation

Answer:
(a) A ray passing through the principal focus of a concave mirror or convex lens, after reflection/refraction, will emerge parallel to the principal axis.
ncert-solutions-class-10th-science-chapter-10-light-reflection-refraction-7

 


Question 8.
Under which of the following conditions, a concave mirror can form an image larger than the actual object? [NCERT Exemplar]
(a) When an object is kept at a distance equal to its radius of curvature
(b) When an object is kept at a distance less than its focal length
(c) When an object is placed between the focus and centre of curvature
(d) When an object is kept at a distance greater than its radius of curvature

Answer/ Explanation

Answer:
(c) A concave mirror can form an image enlarged, real and inverted than the actual object, beyond centre of curvature (C) when object is placed between the focus (F) and centre of curvature.

 


Question 9.
A light ray enters from medium A to medium Bas shown in the figure. The refractive index of medium B relative to A will be [NCERT Exemplar]
ncert-solutions-class-10th-science-chapter-10-light-reflection-refraction-9
(a) greater than unity
(b) less than unity
(c) equal to unity
(d) zero

Answer/ Explanation

Answer:
(a) Since, light rays in the medium B goes towards normal. So, it has greater refractive index and lesser velocity of light w.r.t. medium A. So, refractive index of medium B w.r.t. medium A is greater than unity.

 


Question 10.
Figure shows a ray of light as it travels from medium A to medium B. Refractive index of the medium B relative to medium A is
ncert-solutions-class-10th-science-chapter-10-light-reflection-refraction-10

Answer/ Explanation

Answer:
(a) Given, angle of incidence, i = 60°, angle of refraction, r = 45°
Refractive index of the medium B relative to medium A,
ncert-solutions-class-10th-science-chapter-10-light-reflection-refraction-10.1

 


Question 11.
Beams of light are incident through the holes A and B and emerge out of box through the holes C – and D respectively, as Box shown in the figure.
ncert-solutions-class-10th-science-chapter-10-light-reflection-refraction-11
Which of the following could be inside the box? [NCERT Exemplar]
(a) A rectangular glass slab
(b) A convex lens
(c) A concave lens
(d) A prism

Answer/ Explanation

Answer:
(a) Here, the emergent rays are parallel to the direction of the incident ray. Therefore, a rectangular glass slab could be inside the box as the extent of bending of light ray at the opposite parallel faces AB (air-glass interface) and CD (glass-air interface) of the rectangular glass slab are equal and opposite. This is why the ray emerges parallel to the incident ray.

 


Question 12.
A beam of light is incident through the holes on side A and emerges out of the holes on the other face of the box as shown in the figure. Which of the following could be inside the box? [NCERT Exemplar]
ncert-solutions-class-10th-science-chapter-10-light-reflection-refraction-12
(a) Concave lens
(b) Rectangular glass slab
(c) Prism
(d) Convex lens

Answer/ Explanation

Answer:
(d) Since, in the figure all the parallel rays converge at a point. So, inside the box there must be a convex lens.
ncert-solutions-class-10th-science-chapter-10-light-reflection-refraction-12.1

 


Question 13.
Which of the following statement is true? [NCERT Exemplar]
(a) A convex lens has 4D power having a focal length 0.25 m
(b) A convex lens has 4D power having a focal length -0.25 m
(c) A concave lens has 4D power having a focal length 0.25 m
(d) A concave lens has 4D power having a focal length -0.25 m

Answer/ Explanation

Answer:
(a) The power P of a lens of focal length f is given by
P = 1/f, where f is the focal length in metre and P is the power in dioptre.
P= 1/f or f = 1/P = 1/4 = 0.25 m

 


Question 14.
Magnification produced by a rear view mirror fitted in vehicles [NCERT Exemplar]
(a) is less than one
(b) is more than one
(c) is equal to one
(d) can be more than or less than one depending upon the position of the object in front of it.

Answer/ Explanation

Answer:
(a) The convex mirror forms virtual, erect and diminished image of the object and rear view mirror also form same type of image. Therefore, magnification (m) produced by a rear view mirror fitted in vehicles is less than one, i.e. m < 1.

 


Question 15.
Rays from the Sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed, so that size of its image is equal to the size of the object? [NCERT Exemplar]
(a) 15 cm in front of the mirror
(b) 30 cm in front of the mirror
(c) between 15 cm and 30 cm in front of the mirror
(d) more than 30 cm in front of the mirror

Answer/ Explanation

Answer:
(b) The rays from the Sun, i.e. from infinity, are parallel to principal axis after reflection converge at a point is known as focus. Therefore, focal length if) of concave mirror is 15 cm. And we know that, same size, real and inverted image is formed by concave mirror when object is placed at focus 2 A or centre of curvature, so to form same size of image, object will be placed at 15 x 2 =30 cm.

 


Question 16.
The path of a ray of light coming from air passing through a rectangular glass slab traced by four students shown as I, II, III and IV in the figure. Which one of them is correct? [NCERT Exemplar]
ncert-solutions-class-10th-science-chapter-10-light-reflection-refraction-16
(a) Only I
(b) Only II
(c) Only III
(d) Only IV

Answer/ Explanation

Answer:
(b) In a rectangular glass slab, the emergent rays are parallel to the direction of the incident ray, because the lateral deviation of bending of the ray of light at the opposite parallel faces (air-glass interface) and (glass-air interface) of the rectangular glass slab are equal and opposite. This is why the ray emerges are parallel to the incident ray.

 


Question 17.
You are given water, mustard oil, glycerine and kerosene. In which of these media, a ray of light incident obliquely at same angle would bend the most? [NCERT Exemplar]
(a) Kerosene
(b) Water
(c) Mustard oil
(d) Glycerine

Answer/ Explanation

Answer:
(d) The given material having their refractive index as kerosene is 1.44, water is 1.33, mustard oil is 1.46 and glycerine is 1.74. Thus, glycerine is most optically denser and hence have the largest refractive index. Therefore, ray of light bend most in glycerine.

 


Question 18.
A student placed a light bulb in midway between the two plane mirrors inclined at an angle of 60°. How many images will be observed by him?
(a) 4
(b) 6
(c) 5
(d) 8

Answer/ Explanation

Answer:
(c) Number of images formed by two plane mirrors inclined at an angle 60° when a light bulb is placed in midway between them is
N = 360°/60° – 1 = 6 – 1 = 5

 


Question 19.
Where should an object be placed in front of a convex lens to get a real image of the size of the object? [NCERT]
(a) At the principal focus of the lens
(b) At twice the focal length
(c) At infinity
(d) Between the optical centre of the lens and its principal focus

Answer/ Explanation

Answer:
(b) To set the real image of the size of the object, it should be placed at twice the focal length of a convex lens.

 


Question 20.
Which of the following lenses would you prefer to use while reading small letters found in dictionary? [NCERT]
(a) A convex lens of focal length 50 cm
(b) A concave lens of focal length 50 cm
(c) A convex lens of focal length 5 cm
(d) A concave lens of focal length 5 cm

Answer/ Explanation

Answer:
(c) Convex lens is used as magnifying glass. For better performance its focal length should be small.

 


 

MCQ Questions for Class 10 Science Chapter 11 Human Eye and Colourful World

Question 1.
The human eye forms the image of an object at its [NCERT]
(a) cornea
(b) iris
(c) pupil
(d) retina

Answer/ Explanation

Answer:
(d) Retina is the light sensitive surface of eye on which the image is formed.

 


Question 2.
The human eye can focus objects at different distances by adjusting the focal length of eye lens. This is due to [NCERT]
(a) presbyopia
(b) accommodation
(c) nearsightedness
(d) farsightednes

Answer/ Explanation

Answer:
(b) Accommodation is the ability of eye lens to focus both near and distant objects by adjusting its focal length.

 


Question 3.
The change in focal length of eye lens is caused by action of [NCERT]
(a) pupil
(b) retina
(c) ciliary muscles
(d) iris

Answer/ Explanation

Answer:
(c) Ciliary muscles contract and extend in order to change the lens shape for focussing image ayretina.

 


Question 4.
The least distance of distinct vision for a young adult with normal vision is about [NCERT]
(a) 25 m
(b) 2.5 cm
(c) 25 cm
(d) 2.5 m

Answer/ Explanation

Answer:
(c) The minimum distance at which an object can be seen most distinctly without any strain is 25 cm.

 


Question 5.
At noon the Sun appears white as [NCERT Exemplar]
(a) light is least scattered
(b) all the colours of the white light are scattered away
(c) blue colour is scattered the most
(d) red colour is scattered the most

Answer/ Explanation

Answer:
(a) At noon, the Sun appears white because the light from the Sun is directly over head and travel relatively shorter distance. The Sun appears white as only a little of the blue and violet colours are scattered.

 


Question 6.
A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power [NCERT Exemplar]
(a) +0.5 D
(b) -0.5 D
(c) +0.2 D
(d) -0.2 D
If a person cannot see distinctly, objects kept beyond 21 m, then he is suffering from myopia.

Answer/ Explanation

Answer:
(b) As the person has the eye defect, myopia, therefore a concave lens has to be used whose focal length will be f = -2 m (using sign convention). Thus,
Power, P = 1/f [where, f is focal length in metre.]
= 1/-2 = -0.5D .

 


Question 7.
Which of the following phenomena of light are involved in the formation of a rainbow? [NCERT Exemplar]
(a) Reflection, refraction and dispersion
(b) Refraction, dispersion and total internal reflection
(c) Refraction, dispersion and internal reflection
(d) Dispersion, scattering and total internal reflection

Answer/ Explanation

Answer:
(c) A rainbow is caused by dispersion, refraction and internal reflection of sunlight by tiny water droplets, present in the atmosphere and always formed in a direction opposite to that of the Sun. The water droplets act like small prisms. They refract and disperse the incident sunlight, then reflect it internally and finally refract it again when it comes out of the raindrop.

 


Question 8.
A prism ABC (with BC as base) is placed in different orientations. A narrow beam of white light is incident on the prism as shown in figure. In which of the following cases, after dispersion, the third colour from the top corresponds to the colour of the sky? [NCERT Exemplar]
ncert-solutions-for-class-10th-science-chapter-11-the-human-eye-and-the-colourful-world-8
(a) Only (i)
(b) Only (ii)
(c) Only (iii)
(d) Only (iv)

Answer/ Explanation

Answer:
(b) In (ii) case, after dispersion, the third colour from the top corresponds to colour of the sky, i.e. blue.
ncert-solutions-for-class-10th-science-chapter-11-the-human-eye-and-the-colourful-world-8.1

 


Question 9.
A student sitting on the last bench can read the letters written on the blackboard but is not able to read the letters written in his text book. Which of the following statements is correct?
(a) The near point of his eyes has receded away
(b) The near point of his eyes has come closer to him
(c) The far point of his eyes has come closer to him
(d) The far point of his eyes has receded away
Hypermetropia may have blurred vision to a person when looking at an object close to them and clearer 1 vision while looking at an object at the distance.

Answer/ Explanation

Answer:
(a) The student sitting on the last bench can read the letters written on the blackboard but is not able to read the letters written in his text book because he is suffering from hypermetropia or far sightedness. He can see distant objects clearly but cannot see nearby objects distinctly.

 


Question 10.
In the following diagram, the path of a ray of light passing through a glass prism is shown below.
ncert-solutions-for-class-10th-science-chapter-11-the-human-eye-and-the-colourful-world-10
In this diagram, the angle of incidence, the angle of emergence and the angle of deviation respectively, are [CBSE2014]
(a) X, R and T
(b) Y, Q and T
(c) X, Q and P
(d) Y, Q and P

Answer/ Explanation

Answer:
(d) Angle of incidence is the angle made by the incident ray with the normal to the first surface of prism, which is shown by angle Y. Angle of emergence is the angle made by the emergent ray with the normal to the surface when it comes out from the prism after refraction, which is shown by angle Q. Angle of deviation is the angle between the incident ray and the emergent ray, which is shown by angle P.

 


 

MCQ Questions for Class 10 Science Chapter 12 Electricity

Question 1.
To determine the equivalent resistance of two resistors when connected in series, a student arranged the circuit components as shown in the diagram. But he did not succeed to achieve the objective. [CCE 2010]
ncert-solutions-class-10-science-chapter-12-electricity-1
Which of the following mistakes has been committed by him in setting up the circuit?
(a) Position of ammeter is incorrect
(b) Position of voltmeter is incorrect
(c) Terminals of ammeter are wrongly connected
(d) Terminals of voltmeter are wrongly connected

Answer/ Explanation

Answer:
(c) Because positive terminal of ammeter must be connected with positive terminal of cell and negative terminal of an ammeter must be connected to negative terminal of a cell.

 


Question 2.
For the given circuit, name the components which are connected in parallel. [CCE 2011]
ncert-solutions-class-10-science-chapter-12-electricity-2
(a) R1 and R2
(b) R1, R2 and V
(c) R2 and V
(d) R1 and V

Answer/ Explanation

Answer:
(b) The components R1, R2 and V are connected in parallel combination. Because terminals of the resistance and voltmeter are connected together.

 


Question 3.
A student arranges the following circuit to get equivalent resistance of a series combination of two resistors R1 and R2.
ncert-solutions-class-10-science-chapter-12-electricity-3
Which one of the following statements will be true for this circuit [CCE 2007]
(a) It gives incorrect reading for current I as well as potential difference V
(b) It gives correct reading for current I but incorrect reading for potential difference V
(c) It gives correct reading for potential difference V but incorrect reading for current I
(d) It gives correct reading for both I and V

Answer/ Explanation

Answer:
(b) The voltmeter should be connected across the components of and R2 to give correct reading for potential difference.

 


Question 4.
An ammeter has 20 divisions between 0 mark and 2A mark on its scale. The least count of ammeter is
(a) 0.01A
(b) 0.2A
(c) 0.1A
(d) 1A

Answer/ Explanation

Answer:
(c) Number of divisions = 20
Maximum reading of ammeter = 2 A
Least count of ammeter = 2/20 = 1/10 = 0.1 A

 


Question 5.
A student finds that there are 20 divisions between zero mark and 1V mark of a voltmeter. The least count of voltmeter is
(a) 0.1 V
(b) 0.01 V
(c) 0.05 V
(d) 1.0 V

Answer/ Explanation

Answer:
(c) Number of divisions = 20
Maximum reading of the voltmeter = 1 V
Least count of voltmeter = 1/20 = 0.05 V

 


Question 6.
The current flowing through a resistor connected in an electric circuit and the potential difference applied across its ends are shown in figure alongside.
ncert-solutions-class-10-science-chapter-12-electricity-6
The value of the resistance of the resistor is [CCE2013]
(a) 1 Ω
(b) 5 Ω
(c) 8 Ω
(d) 10 Ω

Answer/ Explanation

Answer:
(d) Reading from ammeter (7) = 180 mA= 0.18 A,
reading from voltmeter (V) = 1.8 V
Resistance of the resistor R = V/I = 1.8/0.18 = 180/18 = 10Ω

 


Question 7.
Which of the following is the correct method to connect the ammeter and voltmeter with resistance in the circuit to verify Ohm’s law? [CCE 2012]
(a) Ammeter and voltmeter in series
(b) Ammeter in series and voltmeter in parallel
(c) Ammeter in parallel and voltmeter in series
(d) Ammeter and voltmeter in parallel

Answer/ Explanation

Answer:
(b) In a circuit, ammeter should be connected in series, while voltmeter in parallel.

 


Question 8.
In an experiment on studying the dependence of the current I flowing through a given resistor on the potential difference V applied across it, a student has to change the value of the current. For doing this, he should change the
(a) number of cells used
(b) resistor itself
(c) ammeter used in the circuit
(d) Voltmeter used in the circuit

Answer/ Explanation

Answer:
(a) If we change the number of cells in electric circuit, the potential difference will change and as a result current flowing in the circuit changes.

 


Question 9.
A milliammeter had graduations marked 0, 100, 200, 300, 400 and 500. The space between 0 mark and 100 mark is divided into 20 divisions. If the pointer of the milliammeter is indicating the seventh graduation after 300 mark, the current flowing in the circuit is
(a) 335 mA
(b) 330 mA
(c) 331mA
(d) 340 mA

Answer/ Explanation

Answer:
(a) Number of divisions = 20
Least count of milliammeter = (100-0) / 20 = 5 mA
Milliammeter reading = 300 + 7 x 5 = 335 mA

 


Question 10.
If a student while studying the dependence of current on the potential difference keeps the circuit closed for a long time to measure the current and potential difference, then
(a) ammeter’s zero error will change
(b) ammeter will give more reading
(c) voltmeter will show constantly higher readings
(d) resistor will get heated up and its value will change

Answer/ Explanation

Answer:
(d) If the circuit is closed for a long time, then current flows in it for a long time which results that the resistor is heated.

 


Question 11.
To determine the eguivalent resistance of two resistors connected in series, a student prepared two electric circuits, correct reading of ammeter in the circuits is [CCE 2015]
ncert-solutions-class-10-science-chapter-12-electricity-11
(a) In circuit I, 1.0 A and in II, 0.1 A
(b) In both circuits I and II, 1.0 A
(c) In circuit I, 0.1 A and in II, 1.0 A
(d) In both circuits I and II, 0.1 A

Answer/ Explanation

Answer:
(b) Equivalent resistance of two resistors 3.5Ω and 1Ω in both the circuits I and II is R = 3.5 + 1 = 4.5 Ω
As, I = V/R = 4.5/4.5 = 1A
Therefore, current in both the circuits I and II is 1.0 A.

 


Question 12.
When parallel resistors are of three different values, the potential difference across its terminals is [CCE 2015]
(a) greatest across smallest resistance
(b) greatest across largest resistance
(c) equal across each resistance
(d) least across the smallest resistance

Answer/ Explanation

Answer:
(c) Potential difference across each resistor is same in parallel combination of resistors.

 


 

MCQ Questions for Class 10 Science Chapter 13 Magnetic Effects of Electric Current

Question 1.
A compass is to be placed near a bar magnet with unknown poles. Outside the magnetic field, the compass needle is pointing towards North as shown below:
ncert-solutions-for-class-10-science-chapter-13-magnetic-effects-of-electric-current-1

Answer/ Explanation

Answer:
(c) Magnetic field lines always point from North pole to South pole around the magnet. Thus, compass needle follows the path difference of magnetic field lines.

 


Question 2.
A bar magnet is broken into three parts X, Y and Z.
ncert-solutions-for-class-10-science-chapter-13-magnetic-effects-of-electric-current-2
Which diagram show the poles in X, Y and Z?
ncert-solutions-for-class-10-science-chapter-13-magnetic-effects-of-electric-current-2.1

Answer/ Explanation

Answer:
(d) When a magnet is broken into three parts X, Y and Z, each part is still a magnet and the strength of the magnetic force remains the same.

 


Question 3.
An unmagnetised iron bar is placed near the end of a bar magnet.
ncert-solutions-for-class-10-science-chapter-13-magnetic-effects-of-electric-current-3
Which of the following diagram is correct?
ncert-solutions-for-class-10-science-chapter-13-magnetic-effects-of-electric-current-3.1

Answer/ Explanation

Answer:
(b) The end of the iron bar nearer to the South pole of the bar magnet becomes induced North pole while the other end is South pole.

 


Question 4.
The diagram shows a current-carrying wire passing through the centre of a square cardboard.
ncert-solutions-for-class-10-science-chapter-13-magnetic-effects-of-electric-current-4
How do the strengths of the magnetic field at points X, Y and Z compare?
(a) equal at X, Y and Z
(b) stronger at Y than X, equal at Y and Z
(c) weaker at Y than Z, stronger at Y than Z
(d) stronger at Y than X, weaker at Z than X

Answer/ Explanation

Answer:
(d) The closer to the wire, the stronger is the magnetic field strength. Since, the magnetic field is circular. Y is the closest followed by X than Z.

 


Question 5.
A circular loop placed in a plane perpendicular to the plane of paper carries a current when the key is on.
ncert-solutions-for-class-10-science-chapter-13-magnetic-effects-of-electric-current-5
The current as seen from points A and B (in the plane of paper and on the axis of the coil) is anti-clockwise and clockwise, respectively.
The magnetic field lines point from B to A. The N-pole of the resultant magnet is on the face close to
(a) A
(b) B
(c) A if the current is small and B if the current is large
(d) B if the current is small and A if the current is large [NCERT Exemplar]

Answer/ Explanation

Answer:
(a) The N-pole of the resultant magnet is on the face close to A because, the magnetic field lines enter in loop from B and come out from A. Also, as a matter of fact magnetic lines come out of the N-pole of magnet. Therefore, face close to A represents N-pole. The currents in A and B are same.

 


Question 6.
A bar magnet is used to pick up an iron nail.
ncert-solutions-for-class-10-science-chapter-13-magnetic-effects-of-electric-current-6
At which parts X, Y and Z is the easiest for the magnet to pick up the iron nail?
(a) At X
(b) AtY
(c) At Z
(d) It makes no difference

Answer/ Explanation

Answer:
(c) The region with the highest density of magnetic field lines has the greatest strength.

 


Question 7.
If the key in the arrangement as shown below is taken out (the circuit is made open) and magnetic field lines are drawn over the horizontal plane ABCD, the lines are [NCERT Exemplar]
ncert-solutions-for-class-10-science-chapter-13-magnetic-effects-of-electric-current-7
(a) concentric circles
(b) elliptical in shape
(c) straight lines parallel to each other
(d) concentric circles near the point O but of elliptical shapes as we go away from it

Answer/ Explanation

Answer:
(c) When the key is taken out (the circuit is made open), no current flows through the wire, hence no magnetic field exists due to the conductor.
The only magnetic field is due to Earth’s magnetic field and are straight lines parallel to each other. The horizontal component is directed from geographical South to geographical North on the horizontal plane ABCD.

 


Question 8.
Four metal rods are placed in turn inside the solenoid to attract paper clips.
The table below gives the results of the experiment when current is switched on and off.

Metalrod

When current is switched on, number of paper clips attracted When current is switched off, number of paper clips still attracted
(a) 1 0
(b) 20 2
(c) 35 0
(d) 35 30

Which rod would be the most suitable to use for the core of the solenoid in a circuit breaker?

Answer/ Explanation

Answer:
(c) The core of the solenoid in a circuit breaker must be made of a soft type magnetic material which can be strongly magnetised but does not retain induced magnetism.

 


Question 9.
Permanent magnets can be made using hard magnetic materials.
Which of the following is not the correct method to make permanent magnets?
(a) Using a bar magnet to stroke a steel bar
(b) Using two bar magnets to stroke a steel bar
(c) Placing a steel bar in a solenoid that connects to a DC supply
(d) Placing a steel bar in a solenoid that connects to an AC supply, then slowly withdrawing the steel bar away from the solenoid in West-East direction

Answer/ Explanation

Answer:
(d) The AC supply will mix up the direction of the magnetic domains. In fact, this is one of the methods to demagnetise magnets.

 


Question 10.
In the arrangement shown in figure, there are two coils wound on a non-conducting cylindrical rod. Initially, the key is not inserted. Then, the key is inserted and later removed. Then,
ncert-solutions-for-class-10-science-chapter-13-magnetic-effects-of-electric-current-10
(a) the deflection in the galvanometer remains zero throughout.
(b) there is a momentary deflection in the galvanometer but it dies out shortly and there is no effect when the key is removed.
(c) there are momentary galvanometer deflections that die out shortly, the deflections are in the same direction.
(d) there are momentary galvanometer deflections that die out shortly, the deflections are in opposite directions. Thus, the galvanometer shows momentary deflections in opposite directions. [NCERT Exemplar]

Answer/ Explanation

Answer:
(d) In the given arrangement, whenever an electric current through the first coil is changed, an emf is induced in the coil due to change in magnetic field lines which pass through the neighbouring second coil. When key is inserted and removed, then the magnetic field lines passing through second coil increases and decreases in two cases respectively. Therefore, the direction of current in two cases is opposite. Thus, the galvanometer shows momentary deflections in opposite directions.

 


 

MCQ Questions for Class 10 Science Chapter 14 Magnetic Effects of Electric Current

Question 1.
Which of the following is a non-renewable source of energy? [NCERT Exemplar]
(a) Wood
(b) Sun
(c) Fossil fuel
(d) Wind

Answer/ Explanation

Answer:
(c) The fossil fuels are non-renewable sources of energy whereas wood, the Sun and wind are renewable sources of energy. Non-renewable sources of energy are those which are exhaustible and cannot be replaced, once they have been used. They are also known as conventional sources of energy.

 


Question 2.
Fuel used in thermal power plant is [NCERT Exemplar]
(a) water
(b) uranium
(c) bio-mass
(d) fossil fuels

Answer/ Explanation

Answer:
(d) The thermal power plant generates electric power from heat produced by burning fossil fuel, i.e. coal and petroleum. Everyday we burn a large amount of fossil fuels to heat up water to produce steam. The steam so produced runs turbines to generate electricity.

 


Question 3.
In a hydroelectric power plant more electrical power can be generated, if water falls from a greater height because [NCERT Exemplar]
(a) its temperature increases
(b) a large amount of potential energy is converted into kinetic energy
(c) the electricity content of water increases with height
(d) more water molecules dissociate into ions

Answer/ Explanation

Answer:
(b) In a hydroelectric power plant, more electrical power can be generated, if water falls from a greater height, because the rise in water level causes the increase in potential energy of water. Thus, when it flows from higher position more amount of kinetic energy is formed by the conversion of higher potential energy and this kinetic energy in the form of moving water can produce more electrical power.

 


Question 4.
The power generated in a windmill [NCERT Exemplar]
(a) is more in rainy season, since damp air would mean more air mass hitting blades
(b) depends on the height of the tower
(c) depends on wind velocity
(d) can be increased by planting tall trees close to the tower

Answer/ Explanation

Answer:
(c) Wind energy farms can be located only in vast open areas located in favourable wind conditions as the minimum velocity for a windmill to functions is 11-16 km/h and is called as cut in speed. Thus, the power generated in a windmill depends on wind velocity.

 


Question 5.
Choose the correct statement. [NCERT Exemplar]
(a) Sun can be taken as an inexhaustible source of energy
(b) There is infinite storage of fossil fuel inside the Earth
(c) Hydro and wind energy plants are non-polluting sources of energy
(d) Waste from a nuclear power plant can be easily disposed off

Answer/ Explanation

Answer:
(a) The Sun has been radiating an enormous amount of energy at the present rate for nearly 5 billion years and will continue radiating at that rate for about 5 billion years more, so the Sun can be taken as an inexhaustible source of energy.

 


Question 6.
Which part of the solar cooker is responsible for greenhouse effect? [NCERT Exemplar]
(a) Coating with black colour inside the box
(b) Mirror
(c) Glass sheet
(d) Outer cover of the solar cooker

Answer/ Explanation

Answer:
(c) Glass sheet present in the solar cooker easily passes the radiation into the solar cooker and the radiation gets absorbed and that reflected back by the black coating is of longer wavelength and cannot pass back out through the glass. Thus, glass sheet produces greenhouse effect in solar cooker.

 


Question 7.
Ocean thermal energy is due to [NCERT Exemplar]
(a) energy stored by waves in the ocean
(b) temperature difference at different levels in the ocean
(c) pressure difference at different levels in the ocean
(d) tides arising out in the ocean

Answer/ Explanation

Answer:
(b) The water at the surface of the sea or ocean is heated by the Sun, while the water in deeper sections is relatively cold. This difference in temperature between these layers ranges from 10-30 °C and is exploited to obtain energy. Thus, ocean thermal energy is due to temperature difference at different levels in the ocean.

 


Question 8.
The major problem in harnessing nuclear energy is how to [NCERT Exemplar]
(a) split nuclei
(b) sustain the reaction
(c) dispose off spent fuel safely
(d) convert nuclear energy into electrical energy

Answer/ Explanation

Answer:
(c) The major hazard of nuclear power generation is the storage and disposal of spent or used fuels. Improper nuclear waste storage and disposal result in environmental contamination as well as risk of accidental leakage of nuclear radiation. It happened in Chernobyl disaster 1986, Fukushima Nuclear disaster 2011 caused great damage to the living beings and habitats.

 


 

MCQ Questions for Class 10 Science Chapter 15 Our Environment

Question 1.
Identify the original source of the energy which flows through a food chain?
(a) Carbon dioxide
(b) Glucose
(c) Oxygen
(d) Sunlight

Answer/ Explanation

Answer:
(d) All the living organisms get energy directly or indirectly from the sunlight reaching the surface of Earth.

 


Question 2.
A teacher draws the pyramid of energy on board and writes A, B, C and D, in each trophic level as shown in the diagram given alongside. Which level represents the herbivores?
ncert-solutions-class-10th-science-chapter-15-environment-2
(a) A
(b) B
(c) C
(d) D

Answer/ Explanation

Answer:
(c) The trophic levels represent the transfer of food or energy through various steps or levels in the food chain. Producers harness the maximum energy followed by primary consumers, i.e. a herbivore, which is represented by C in thg given diagram.

 


Question 3.
Which of the following groups contains only biodegradable items? [NCERT]
(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit-peels, cake and lime-juice
(d) Cake, wood and grass

Answer/ Explanation

Answer:
(a), (c) and (d) substances that are broken down (decomposed) by the biological processes are said to be biodegradable e.g. fruit-peels, cake, lime-juice, wood, grass, leather, flowers, etc.

 


Question 4.
Which of the following constitutes a food-chain? [NCERT]
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat

Answer/ Explanation

Answer:
(b) Each step of food chain form a trophic level. Producers (grass) forms the first trophic level, herbivore (goat) the second and carnivore (human) the third trophic level.

 


Question 5.
Which of the following are environment- friendly practices? [NCERT]
(a) Carrying cloth-bags to put purchases ‘ while shopping .
(b) Switching off unnecessary light and fans
(c) Walking to school instead of getting your mother to drop you on her scooter
(d) All of the above

Answer/ Explanation

Answer:
(d) Cloth-bags are biodegradable, switching off unnecessary light and fans conserves electricity and limited use of petrol/diesel causes less pollution. Hence, all these practices are considered as environment friendly.

 


Question 6.
Which of the following statements about food chain are correct?
(a) It includes repeated eating, i.e. each group eats the other and is subsequently eaten by some other group of organisms.
(b) It shows a series of branching lines and unidirectional flow of energy.
(c) It shows the unidirectional flow of energy and proceeds in a progressive straight line.
(d) Both (a) and (c)

Answer/ Explanation

Answer:
(d) A food chain is a series of organisms in an environment through which energy transfer occurs starting with a producer. It proceeds in straight line. Food chain does not consist of branching lines.

 


Question 7.
In class, the teacher explained the concept of food chain and energy flow. She made a diagram as given below and asked the students to identify the producer organism in the chain. What do you think will be the student’s answer?
ncert-solutions-class-10th-science-chapter-15-environment-7

Answer/ Explanation

Answer:
(b) Cabbage is the producer component of this chain. It produces food using sunlight and other components by photosynthesis process. Others are all consumers.

 


Question 8.
An ecosystem includes
(a) all living organisms
(b) non-living objects ,
(c) both living organisms and non-living objects
(d) sometimes living organisms and sometimes non-living objects

Answer/ Explanation

Answer:
(c) All the interacting organisms in an area taken together with the non-living constituents of the environment form an ecosystem. Thus, an ecosystem consists of biotic components including all living organisms and abiotic components constituting physical factors like temperature, rainfall, wind, soil and minerals.

 


Question 9.
In the following groups of materials, which group (s) contains only non-biodegradable items?
(i) Wood, paper, leather
(ii) Polythene, detergent, PVC
(iii) Plastic, detergent, grass
(iv) Plastic, bakelitC DDT
(a) (iii)
(b) (iv)
(c) (i) and (iii)
(d) (ii) and (iv)

Answer/ Explanation

Answer:
(d) Substances that cannot be broken down by biological processes in nature are non-biodegradable. e.g. polythene, detergent, PVC, plastics, bakelite, DDT, etc. On the other hand, substances that are broken down (decomposed) by biological processes are said to be biodegradable, e.g. wood, paper, leather, grass, animal bones, etc.

 


Question 10.
Which of the following statement is incorrect?
(a) All green plants and blue-green algae are producers.
(b) Green plants get their food from organic compounds.
(c) Producers prepare their own food from inorganic compounds.
(d) Plants convert solar energy into chemical energy.

Answer/ Explanation

Answer:
(b) Green plants prepare their food from inorganic compounds using radiant energy of the sun in the presence of chlorophyll. All green plants and blue-green algae are called producers as they can prepare food from inorganic substances by photosynthesis. Producers capture the solar energy and convert it into chemical energy.

 


Question 11.
What will happen if deer is missing in the food chain given below?
Grass → Deer → Tiger
(a) The population of tiger increases.
(b) The population of grass decreases.
(c) Tiger will start eating grass.
(d) The population of tiger decreases and the population of grass increases.

Answer/ Explanation

Answer:
(d) If deer is missing in the given food chain, there will not be sufficient food for the tigers. Some of the tigers will die because of starvation and hence, the population of tigers will decrease. Since, grass is eaten by deers, the population of grass will also increase whefl deer is missing.

 


Question 12.
In a class activity, two students were asked to collect different items from their fellow mates and classify them as biodegradable and non- biodegradable. All the items have been identified except three. Find out which one is non-biodegradable among these?
(a) Jute crafted bag
(b) A sharpner
(c) Empty fevistick
(d) Both (b) and (c)

Answer/ Explanation

Answer:
(d) Both (b) and (c), i.e. the sharpener and the empty fevistick container. These products are made from plastic and hence are non-biodegradable.

 


Question 13.
The diagram shows excretory losses from a rat to the environment.
ncert-solutions-class-10th-science-chapter-15-environment-13
Which of the following will not be returned to the ecosystem and recycled?
(a) carbon dioxide
(b) heat energy
(c) salts
(d) urea

Answer/ Explanation

Answer:
(b) Heat energy cannot be recycled, it gets lost in the environment. The generated is returned through the carbon cycle. Salts are used by living organisms present in the ecosystem. Urea also returns to the nitrogen cycle.

 


Question 14.
Which of the following limits the number of trophic levels in a food chain?
(a) Decrease in energy at higher trophic levels
(b) Deficient food supply
(c) Polluted air
(d) Water

Answer/ Explanation

Answer:
(a) Decrease in energy at higher trophic levels limits the number of trophic levels in a food chain. At each trophic level, a large portion of energy is utilised for the maintenance of organisms that occur at that trophic level. So, organisms at higher level gets less and less energy at successive levels. The. number of trophic levels are limited to 3-4 because after that, the energy available for the next level will be too small, i.e. it will be insufficient to sustain life of the organisms.

 


Question 15.
If a grasshopper is eaten by a frog, then the energy transfer will be from
(a) producer to decomposer
(b) producer to primary consumer
(c) primary consumer to secondary consumer
(d) secondary consumer to primary consumer

Answer/ Explanation

Answer:
(c) In a food chain, if a grasshopper is eaten by a frog, then the energy transfer will be from primary consumer to secondary consumer. Grasshopper feeds on producers i.e. the grass/plants. So, it occupies the level of primary consumer. Frogs, eating grasshopper thus become the secondary consumer.

 


Question 16.
In the given food chain, suppose the amount of energy at fourth trophic level is 5 kJ, what will be the energy available at the producer level?
Grass → Grasshopper → Frog → Snake → Hawk
(a) 5 kJ
(b) 50 kJ
(c) 500 kJ
(d) 5000 kJ

Answer/ Explanation

Answer:
(d) According to 10% law, only 10% of the energy entering a particular trophic level of organisms is available for transfer to the next higher trophic level. In this food chain, at the 4th trophic level, only 5 kJ energy is available to the snake. So, the energy available at the producer level will be 5000 kJ.
It can be shown as
ncert-solutions-class-10th-science-chapter-15-environment-16

 


 

MCQ Questions for Class 10 Science Chapter 16 Management of Natural Resources

Question 1.
Manu and Dheer goes to same school, but their parents drop and pick them separately. After learning about natural resources and their management, they talked to their parents, who arrived on few decisions. What could be the best possible decisions among those given below.
(a) To walk the small distance to school
(b) Car pool
(c) Use common school bus at nearby stop
(d) All of the above

Answer/ Explanation

Answer:
(d) To save the resources like petrol and diesel used in cars, one can walk to their destination, if it is close, car pooling can be done by people sharing same locations, etc. These practice will save the natural resources and reduce environmental pollution.

 


Question 2.
The pH of water sample collected from a river . was found to be acidic in the range of 3.5 – 4.5. On the banks of the river were several factories that were discharging effluents into the river. The effluents of which one of the following factories is most likely to cause low pH of river water? [NCERT Exemplar]
(a) Soap and detergent factory
(b) Lead battery manufacturing factory
(c) Plastic cup manufacturing factory
(d) Alcohol distillery

Answer/ Explanation

Answer:
(b) Lead is a major constituent of lead-acid battery used extensively in car batteries. The discharge from lead battery manufacturing factory can lower the pH of river water by making it acidic.

 


Question 3.
Varun has read about some national movements associated with conserving environment and its resources. Chipko movement was one tree hugging movement in which the villagers compelled axemen to stop the cutting of trees by embracing and encircling trees. Help him in finding out the person who was not related with this movement?
(a) Rajendera Singh
(b) Gaura Devi
(c) Sunder Lai Bahuguna
(d) Chandi Prasad Bhatt

Answer/ Explanation

Answer:
(a) Rajendra Singh was not associated with the Chipko movement. Chipko movement was meant for protection of trees from excessive commercial exploitation and was instigated by Sunder Lai Bahuguna and Chandi Prasad Bhatt.

 


Question 4.
Due to several human activities, waterbodies are polluted resulting in decreased availability of usable water. Maya was testing the samples of polluted water in lab. The presence of which factor will confirm to her that the water sample is polluted.
Select the correct option.
(a) The presence of coliform bacteria
(b) High BOD
(c) Both (a) and (b)
(d) Either (a) or (b)

Answer/ Explanation

Answer:
(c) In polluted water sample, coliform bacteria are present. Biochemical Oxygen Demand is BOD. High BOD indicates that water is polluted.
Coliform bacteria occurs in waterbodies where human excreta and deadbodies are disposed off.

 


Question 5.
The construction of large dams has faced a lot of oppositions like the Sardar Sarovar Project on river Narmada lead to Narmada Bachao Andolan. Raj has to identify the correct problem that lead to such strong oppositions against construction of such dams.
Choose the correct option.
(a) Large areas of agricultural land and human habitation submerged
(b) Destruction of large ecosystem and loss of biological diversity
(c) Displacement of large number of local population without adequate rehabilitation
(d) All of the above

Answer/ Explanation

Answer:
(d) All the given statements are correct. Construction of large dams leads to disappearance of agricultural land, disposal of human habitation.
Thus, disturbing an ecosystem along with its diversity. People are displaced from their homes ” without any recommendation of living space and profession.

 


Question 6.
Ganga has been considered as a symbol of purity but is grossly polluted by waste dumped in it. Government has been making plans to revive this basin. Which steps should according to you be incorporated in the plan to prevent any further polluting of this river? Choose the correct option.
(a) Renovation of sewage pumps and treatment plants
(b) Extension of sewerage in unsewered areas to bring waste from those areas to treatment plants
(c) Installation of new treatment plants
(d) All of the above

Answer/ Explanation

Answer:
(d) All the strategies can be incorporated in the plan of action to make river Ganga pollution free.

 


Question 7.
Madhur was reading about rainwater harvesting and its benefits. He came to learn about different types of structures that are build in different states to conserve rainwater. Select the correct option which represent such structures.
(a) Bhundhis
(b) Khadins
(c) Both (a) and (b)
(d) Compost pit

Answer/ Explanation

Answer:
(c) Khadins and Bhundhis are the traditional rain harvesting systems used in Rajasthan and Madhya Pradesh, Uttar Pradesh, respectively.

 


Question 8.
A student reading an article on sustainable development came across some statements which confused him. Those statements are being given below.
Choose the incorrect statement from therm by selecting an option.
(a) Economic development is linked to environmental conservation
(b) Sustainable development encourages development for current generation and conservation of resources for future generations
(c) Sustainable development does not consider the view points of stakeholders
(d) Sustainable development is a long planned and persistent development

Answer/ Explanation

Answer:
(c) Statement (c) is incorrect because sustainable development do consider the interest of stakeholders, i.e. people with dependency on the natural resources and are affected by any project or its outcome directly or indirectly.

 


Question 9.
A programme called “silviculture” was started to replenish the forest resource, so as to meet the diverse needs of living beings. According to you, which statements from those given below will not be considered an advantage of this initiative.
(a) It maintains a perfect water cycle in nature
(b) It prevents soil erosion.
(c) It encourages plantation of multipurpose trees in open lands of urban area
(d) It produces a large quantity of raw materials for industry

Answer/ Explanation

Answer:
(c) Silviculture encourages plantation of multipurpose trees in open lands of urban area is not advantageous because they can be cut down when necessity for more land crops up is required.

 


Question 10.
Many international treaties and protocols have been developed and signed by different countries to reduce production of greenhouse gases and environment pollution. A treaty/protocol to reduce C02 emission was
(a) Montreal protocol (1987)
(b) Kyoto protocol (1997)
(c) Helesinki declaration (1989)
(d) None of the above

Answer/ Explanation

Answer:
(b) The Kyoto protocol was signed by various countries pledging to regulate the emissions of CO2. India signed this protocol in Aug. 2002 and has reduced its CO2 emission by 5.2% till now.

 


 

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