ICSE Chemistry Previous Year Question Paper 2019 Solved for Class 10

• Answers to this Paper must be written on the paper provided separately.
• You will not be allowed to write during the first IS minutes.
• This time is to be spent in reading the Question Paper.
• The. time given at the head of this paper is the time allowed for writing the answers.
• Section I is compulsory. Attempt any four questions from Section II.
• The intended marks for questions or parts of questions are given in brackets [ ].

Section -1 [40 Marks]
(Attempt all questions from this Section)

Question 1.
(a) Choose the correct answer from the options given below: [5]
(i) An electrolyte which completely dissociates into ions is :
(A) Alcohol
(B) Carbonic acid
(C) Sucrose
(D) Sodium hydroxide
(D) Sodium hydroxide

(ii) The most electronegative element from the following elements is :
(A) Magnesium
(B) Chlorine
(C) Aluminium
(D) Sulphur
(B) Chlorine

(iii) The reason for using Aluminium in the alloy duralumin is:
(A) Aluminium is brittle
(B) Aluminium gives strength
(C) Aluminium brings lightness
(D) Aluminium lowers melting point
(C) Aluminium brings lightness

(iv) The drying agent used to dry HCl gas is :
(A) Cone. H2SO4
(B) ZnO
(C) Al2O3
(D) CaO
(A) Cone. H2SO4

ICSE Class 10 Chemistry Previous Years Question Papers Solved Last 10 Years

(v) A hydrocarbon which is a greenhouse gas is :
(A) Acetylene
(B) Ethylene
(C) Ethane
(D) Methane
(D) Methane

(b) Fill in the blanks with the choices given in brackets: [5]
(i) Conversion of ethanol to ethene by the action of concentrated sulphuric acid is an example of ……………..
(dehydration / dehydrogenation / dehydrohalogenation)
dehydration

(ii) When sodium chloride is heated with concentrated sulphuric acid below 200°C, one of the products formed is ………………
(sodium hydrogen sulphate / sodium sulphate / chlorine)
sodium hydrogen sulphate

(iii) Ammonia reacts with excess chlorine to form ………………..
(nitrogen / nitrogen trichloride / ammonium chloride)
nitrogen trichioride

(iv) Substitution reactions are characteristic reactions of ……………..
(alkynes / alkenes / alkanes)
alkanes

(v) In Period 3, the most metallic element is ……………..
(sodium / magnesium / aluminium)
sodium

(c) Write a balanced chemical equation for each of the following reactions: [5]
(i) Reduction of copper (II) oxide by hydrogen.
CuO+H→ Cu+H2O

(ii) Action of dilute sulphuric acid on sodium hydroxide.
2NaOH + H2S04 → Na2SO4 + 2H2O

(iii) Action of dilute sulphuric acid on zinc sulphide.
ZnS + H2SO4 → ZnSO4 + H2S

(iv) Ammonium hydroxide is added to ferrous sulphate solution.
FeSO4 + 2NH40H → (NH4)SO4 + Fe(OH)2

(v) Chlorine gas is reacted with ethene.

(d) State one observation for each of the following: [5]
(i) Concentrated nitric acid is reacted with sulphur.

Dense brown fumes of nitrogen dioxide gas will be released

(ii) Ammonia gas is passed over heated copper (II) oxide.

The black colour copper oxide will change to reddish pink copper.

(iii) Copper sulphate solution is electrolysed using copper electrodes.
When copper sulphate solution is electrolysed using copper electrodes, reddish pink deposit of copper metal takes place on cathode.

(iv) A small piece of zinc is added to dilute hydrochloric acid.
Zn + 2HCl > ZnCl2 + H2
Zinc metal dissolves forming solution with the liberation of hydrogen gas which bums with blue flame and gets extinguished with pop sound.

(v) Lead nitrate is heated strongly in a test tube.

White powder of lead nitrate decompose to form yellow coloured lead oxide and liberating dense brown fumes of nitrogen dioxide gas.

(e) (i) Calculate: [5]
1. The number of moles in 12 g of oxygen gas. [O = 16]
2. The weight of 1022 atoms of carbon.
[C = 12, Avogadro’s No. = 6 × 1023]
1. Oxygen gas (O2)
Molecular mass = 16 x 2 = 32 g
32 g of oxygen gas → 1 mole
1 g of oxygen gas → $\frac { 1 }{ 32 }$ mole
12 g of oxygen gas → $\frac { 1 }{ 32 }$ × 12mole = 0.375 mole

2. 6.022 x 1023 atoms of carbon weigh → 12 g
1 atom of carbon weighs → $\frac{12}{6 \times 10^{23}}$
1022 atoms of carbon will weigh → $\frac{12}{6 \times 10^{23}} \times 10^{22}=\frac{12}{60}=\frac{1}{5}$ = 0.2 g

(ii) Molecular formula of a compound is C6H18O3. Find its empirical formula.
Molecular formula = C6H18O3
Take the common multiple
Molecular formula = (C2H60)3
Molecular formula = (Empirical formula)„
Thus, empirical formula = C2H6O

(f) (i) Give the IUPAC name of the following organic compounds: [5]
1.
2.
1. Prop – 1 – yne or propyne
2. Ethanal

(ii) What is the special feature of the structure of ethyne ?
Ethanal

Special feature of the structure of ethyne is the presence of triple bond.

(iii) Name the saturated hydrocarbon containing two carbon atoms.
Ethane

(iv) Give the structural formula of Acetic acid.
Acetic acid (CH3COOH)

(g) Give the appropriate term defined by the statements given below: [5]
(i) The formula that represents the simplest ratio of the various elements present in one molecule of the compound.
Empirical formula

(ii) The substance that releases hydronium ion as the only positive ion when dissolved in water.
Acid

(iii) The tendency of an atom to attract electrons totvards itself when combined in a covalent compound.
Electronegativity

(iv) The process by which certain ores, specially carbonates, are converted to oxides in the absence of air.
Calcination

(v) The covalent bond in-which the electrons are shared equally between the combining atoms.
Non-polar covalent bond

(h) Arrange the following according to the instructions given in brackets : [5]
(i) K, Pb, Ca, Zn. (In the increasing order of the reactivity)
Pb < Zn < Ca < K
(According to the position in reactivity series)

(ii) Mg2+, Cu2+, Na1+, H1+ (In the order of preferential discharge at the cathode)
Na1+ < Mg2+ < H1+ < Cu2+
(According to electrochemical series of metals)

(iii) Li, K, Na, H (In the decreasing order of their ionization potential)
H > Li > Na > K
(Smaller the size greater is the ionization potential)

(iv) F, B, N, O (In the increasing order of electron affinity)
B < N < O < F
(Smaller the size more is the electron affinity)

(v) Ethane, methane, ethene, ethyne. (In the increasing order of the molecular weight)
[H = 1, C = 12]

Section – II [40 Marks]
(Attempt any four questions from this Section)

Question 2.
(a) Draw the electron dot structure of : [3]
(i) Nitrogen molecule [N = 7]
Nitrogen molecule

Nitrogen atom shares three electrons forming a triple covalent bond.

(ii) Sodium chloride [Na = 11, Cl = 17]
Sodium chloride

Sodium loses one electron to chlorine forming a positive ion and chlorine gains one electron forming a negative ion. These ions form an electrovalent bond and are held strongly by electrostatic forces of attraction.

(iii) Ammonium ion [N = 7, H = 1]
Ammonium ion
N (7) →
H (1) → Hx
Formation of ammonia

Formation of proton
H – 1e H+
Formation of ammonium ion
Ammonia donates its lone pair to proton forming ammonium ion.

(b) The pH values of three solutions A, B and C are given in the table. Answer the following questions: [3]

(i) Which solution will have no effect on litmus solution?
(ii) Which solution will liberate CO2 when reacted with sodium carbonate?
(iii) Which solution will turn red litmus solution blue?
(i) C (Because pH 7 is neutral).
(ii) B (Because acids liberate CO2 gas when treated with carbonates and acids have pH less than 7)
(iii) A (Bases turn red litmus blue and they have pH more than 7)

(c) Study the extract of the Periodic Table given below and answer the questions that follow. Give the alphabet corresponding to the element in question. DO NOT repeat an element. [4]
(i) Which element forms electrovalent compound with G?
(ii) The ion of which element will migrate towards the cathode during electrolysis?
(iii) Which non-metallic element has the valency of 2?
(iv) Which is an inert gas?
(i)

(ii) A [Positive ions migrate towards cathode, hence A will form A+ and migrate towards cathode]
(iii) E
(iv) F

Question 3.
(a) Name the particles present in:
(i) Strong electrolyte
(ii) Non-electrolyte
(iii) Weak electrolyte
(i) Only ions
(ii) molecules
(iii) Ions as well as molecules

(b) Distinguish between the following pairs of compounds using the reagent given in the bracket. [3]
(i) Manganese dioxide and copper (II) oxide, (using concentrated HCl)

(ii) Ferrous sulphate solution-and ferric sulphate solution, (using sodium hydroxide solution)

(iii) Dilute hydrochloric acid and dilute sulphuric acid, (using lead nitrate solution)

(c) Choose the method of preparation of the following salts, from the methods given in the list: [4]
[List: A. Neutralization
B. Precipitation
C. Direct combination
D. Substitution]
(ii) Iron (II) sulphate
(iii) Sodium nitrate
(iv) Iron (III) chloride
(ii) Iron (II) sulphate → Substitution (D)
(in) Sodium nitrate → Neutralisation (A)
(iv) Iron (III) chloride → (Direct combination) (C)

Question 4.
(a) Complete the following equations : [3]
(i) S + cone. HNO3
(ii) C + cone. H2SO4
(iii) Cu + dil.HNO3
(i) S + 6HNO3 → H2 SO4 + 6NO2 + 2H2O
(ii) C + 2H2 SO4 → 2H2O + CO2 + 2S02
(iii) 3Cu + 8HNO3 → 3CU(NO3 )2 + 2NO + 4H2O

(b) Write a balanced chemical equation for the preparation of: [3]
(i) Ethene from bromoethane
+ KOHf (alc.) CH2 = CH2 + KBr+H2O

(ii) Ethyne using calcium carbide

(iii) Methane from sodium acetate.

(c) Name the following organic compounds : [4]
(i) The compound with 3 carbon atoms whose functional group is a carboxyl.
(ii) The first homologue whose general formula is CnH2n.
(iii) The compound that reacts with acetic acid to form ethyl ethanoate.
(iv) The compound formed by complete chlorination of ethyne.
(i) propanone
(ii) ethene
(iii) ethanol
(iv) 1,1,2,2 tetrachloro ethane

Question 5.
(a) Give the chemical formula of: [3]
(i) Bauxite
(ii) Cryolite
(iii) Sodium aluminate
(i) Al2O3. 2H2O
(ii) Na3AlF6
(iii) NaAlO92

(b) Answer the following questions based on the extraction of aluminium from alumina by Hall – Heroult’s Process: [3]
(i) What is the function of cryolite used along with alumina as the electrolyte?
(ii) Why is powdered coke sprinkled on top of the electrolyte?
(iii) Name the electrode, from which aluminium is collected.
(i) Cryolite acts as a solvent and lower the fusion temperature from 2050°C to 950°C.
(ii) A layer of powdered coke is sprinkled over the surface of the electrolyte to reduce the heat loss by radiation and prevent the carbon rod from binning in air.
(iii) Cathode

(c) Match the alloys given in column I to the uses given in column II:

(i) Duralumin → Aircraft body
(ii) Solder → Electrical fuse
(iii) Brass → Decorative articles
(iv) Stainless steel → Surgical instruments

Question 6.
(a) Identify the substances underlined: [3]
(i) The catalyst used to oxidise ammonia.
(ii) The organic compound which when solidified- forms an ice like mass.
(iii) The dilute acid which is an oxidizing agent.
(i) Platinum
(ii) Acetic acid
(iii) Nitric acid

(b) Copper sulphate solution reacts with sodium hydroxide solution to form a precipitate of copper hydroxide according to the equation : [3]
2NaOH + CuSO4 → Na2SO4 + Cu(OH)2
(i) What mass of copper hydroxide is precipitated by using 200 gm of sodium hydroxide ? [H = 1, O = 16, Na = 23, S = 32, Cu = 64]

98 g of CU(OH)2 is precipitated by using 80 g of NaOH
l g of CU(OH)2 is preapitated by using $\frac { 80 }{ 98 }$g of NaOH
200 g of CU(OH>2 is preapitated by using $\frac{80}{98} \times 200 g$ = 163.26 g of NaOH

(ii) What is the colour of the precipitate formed ?
Pale blue precipitates

(c) Find the empirical formula and the molecular formula of an organic compound from the data given below:
C = 75.92%, H = 6.32% and N = 17.76%
The vapour density of the compound is 39.5.
[C= 12, H= 1,N= 14] [4]

Empirical Formula ⇒ C5H5 N
Vapour density = 39.5
Molecular Mass = 2 × V.D.
= 2 × 39.5 = 79
Empirical formula Mass = 12 × 5 + 5 × 1 + 1 × 14
= 60 + 5 + 14
= 79
n = $\frac { Molecular formula mass }{ Empirical formula mass }$= $\frac { 79 }{ 79 }$
Thus, both Empirical formula and Molecular formula are C3H5N.

Question 7.
(a) Name the gas evolved in each of the following cases : [3]
(i) Altunina undergoes electrolytic reduction.
(ii) Ethene undergoes hydrogenation reaction
(iii) Ammonia reacts with heated copper oxide
(i) Oxygen
(ii) Ethane
(iii) Nitrogen

(b) Study the flow chart given and give balanced equations to represent the reactions A, B and C.
(A) Mg3N2 + 6H2O → 3Mg(OH)2 + 2NH3
(B) NH3+ HCl → NH4C1
(C)

(c) Copy and complete the following table which refers to the industrial method for the preparation of ammonia and sulphuric acid : [4]