Students should refer to ICSE Class 10 Chemistry Question Paper solved Set C given below which will help them to prepare for the upcoming ICSE Chemistry exams. Students should read ICSE Chemistry Class 10 Books to make sure they are completely prepared and should also refer to ICSE Class 10 Chemistry Solutions to understand all questions and their answers.
ICSE Class 10 Chemistry Question Paper solved Set C
PAPER 2 (CHEMISTRY)
Answers to this Paper must be written on the paper provided separately.
You will not be allowed to write during the first 15 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 [ ].
ICSE Class 10 Chemistry Question Paper solved Set C
SECTION – I (40 MARKS)
(Attempt all questions from this Section)
(a) Select from the list the gas that matches the description given in each case: [ammonia, ethane, hydrogen chloride, hydrogen sulphide, ethyne]
(i) This gas is used as a reducing agent in reducing copper oxide to copper.
(ii) This gas produces dense white fumes with ammonia gas.
(iii) This gas is used for welding purposes.
(iv) This gas is also a saturated hydrocarbon.
(v) This gas has a characteristic rotten egg smell. 
(ii) Hydrogen chloride
(iii) Ethyne (iv) Ethane
(v) Hydrogen sulphide
(b) Choose the most appropriate answer for each of the following:
(i) Among the elements given below, the element with the least electronegativity is:
(ii) Identify the statement which does not describe the property of alkenes:
(A) They are unsaturated hydrocarbons
(B) They decolourise bromine water
(C) They can undergo addition as well as substitution reactions
(D) They undergo combustion with oxygen forming carbon dioxide and water.
(iii) This is not an alloy of copper:
(iv) Bonding in this molecule can be understood to involve coordinate bonding.
(A) Carbon tetrachloride
(C) Hydrogen chloride
(D) Ammonium chloride
(v) Which of the following would weigh the least?
(A) 2 gram atoms of Nitrogen.
(B) 1mole of Silver
(C) 22.4 litres of oxygen gas at 1 atmospheric pressure and 273K
(D) 6.02 . 1023 atoms of carbon.
[Atomic masses: Ag=108, N=14, O=16, C=12] 
(i) (A) Lithium
Lithium is an element with the least electronegativity.
(ii) (C) They can undergo addition and substitution reactions.
Alkenes do not undergo substitution reaction.
(iii) (C) Solder
Solder is an alloy of lead and tin.
(iv) (D) Ammonium chloride
The bond formed between the nitrogen atom in ammonia and the chloride ion is a coordinate bond.
(v) (D) 6.02 . 1023 atoms of carbon.
(c) Complete the following calculations. Show working for complete credit:
(i) Calculate the mass of Calcium that will contain the same number of atom as are present in 3.2 gm of Sulphur. [Atomic masses: S=32, Ca=40] 
(ii) If 6 litres of hydrogen and 4 litres of chlorine are mixed and exploded and if water is added to the gases formed, find the volume of the residual gas. 
(iii) If the empirical formula of a compound is CH and it has a vapour density of 13, find the molecular formula of the compound.
Mass of Sulphur = 3.2 gm
32 g of S º 6.022 × 1023 atoms
3.2 g of S º ?
3.2 g of S will contain = 6.022 x1023 x 3.2 / 32
= 6.02 × 1022 atom
40 g of Ca º 6.02 × 1023 atoms
? = 6.02 × 1022 atoms
Mass of Ca = 40 x 6.02 x 1023 / 6.02 x1022 = 4g
Mass of calcium = 4 g
(ii) 6 litres of hydrogen and 4 litres of chlorine are mixed which results in the formation of 8 litres of HCl gas. When water is added, it results in the formation of hydrochloric acid. So, the amount of gas left is only 2 litres of hydrogen as chlorine acts as a limiting reagent.
Therefore, the volume of the residual gas will be 2 litres.
Empirical formula = CH
Vapour density = 13
Molecular weight = 2 × Vapour density
= 2 × 13 = 26
∴ Empirical formula of a compound with molecular mass 26 is CH.
∴ Molecular formula of the given compound is 2 × (CH) = (CH)2 = C2H2.
(d) State one relevant observation for each of the following:
(i) When crystals of copper nitrate are heated in a test tube.
(ii) When the gaseous product obtained by dehydration of ethyl alcohol is passed through bromine water.
(iii) When hydrogen sulphide gas is passed through lead acetate solution.
(iv) When ammonia gas is burnt in an atmosphere of excess oxygen.
(v) At the Anode when aqueous copper sulphate solution is electrolysed using copper electrodes.
(i) Reddish brown nitrogen dioxide gas is released and the residue left behind is black copper oxide.
(ii) The reddish brown colour of bromine solution gets decolourised.
(iii) When hydrogen sulphide gas is passed through lead acetate solution, it forms a black precipitate of lead sulphide.
(iv) Ammonia gas burns to form nitrogen gas and steamy fumes of water.
Also it burns with greenish yellow flame.
(v) The anode slowly dissolves, but the colour of copper sulphate does not change.
(e) Identify the acid which matches the following description (i) to (v):
(i) The acid which is used in the preparation of a non-volatile acid.
(ii) The acid which produces sugar charcoal from sugar.
(iii) The acid which is prepared by catalytic oxidation of ammonia.
(iv) The acid on mixing with lead nitrate solution produces a white precipitate which is insoluble even on heating.
(v) The acid on mixing with silver nitrate solution produces a white precipitate which is soluble in excess ammonium hydroxide.
Ans. (i) Concentrated Nitric Acid
(ii) Conc. sulphuric acid
(iii) Conc. Nitric acid
(iv) Dilute sulphuric acid
(v) Dilute hydrochloric acid
(f) Give appropriate scientific reasons for the following statements:
(i) Zinc oxide can be reduced to zinc by using carbon monoxide, but aluminium oxide cannot be reduced by a reducing agent
(ii) Carbon tetrachloride does not conduct electricity.
(iii) During electrolysis of molten lead bromide graphite anode is preferred to other electrodes.
(iv) The electrical conductivity of acetic acid is less in comparison to the electrical conductivity of dilute sulphuric acid at a given concentration.
(v) Electrolysis is of molten lead bromide is considered to be a redox reaction. 
(i) The metals in the middle of the activity series like zinc are moderately reactive, and carbon is a good reducing agent because of which zinc oxide gets easily reduced by carbon. Oxides of highly active metals like aluminium have great affinity towards oxygen and so cannot be reduced by carbon.
(Note: Error in the question. Zinc oxide can be reduced to zinc metal by using carbon, but aluminium oxide cannot be reduced by a reducing agent.)
(ii) Carbon tetrachloride is made of individual covalently bonded molecules, CCl4. In addition, the charged particles are absent in CCl4 which could conduct electricity. So, CCl4 does not conduct electricity.
(iii) During the electrolysis of molten lead bromide, a graphite anode is preferred because graphite remains unaffected by the reactive bromine vapours which are released at the anode.
(iv) Sulphuric acid is a strong acid compared to acetic acid. A strong acid has more ions than a weak one, and so, its solution will be a better electrical conductor than a weak acid. So, electrical conductivity of acetic acid is less in comparison of electric conductivity of sulphuric acid.
(v) In the electrolysis of molten lead bromide, the following reactions take place:
At the cathode: Pb2+ (l) + 2e– → Pb(l)
At the anode: 2Br– (l) → Br2 (g) + 2e–
Lead (II) ions (Pb2+) are attracted to the negative electrode, and the Pb2+ ions are forced to accept two electrons. Pb2+ ions are reduced. Bromide ions (Br-) are attracted to the positive electrode and the bromide ions are forced to give away their extra electron to form bromine atoms. Thus, bromide ions are oxidised. So, electrolysis of molten lead bromide is a redox reaction.
(i) Give balanced chemical equations for the following conversions A, B and C:
(ii) Differentiate between the terms strong electrolyte and weak electrolyte. 
(stating any two differences)
(h) Answer the following questions:
(i) Explain the bonding in methane molecule using electron dot structure. 
(ii) The metal of Group 2 from top to bottom are Be, Mg, Ca, Sr, and Ba.
(1) Which one of these elements will form ions most readily and why?
(2) State the common feature in the electronic configuration of all these elements. 
Ans. (i) Formation of methane molecule – Non-polar covalent compound:
One atom of carbon shares four electron pairs, one with each of the four atoms of hydrogen.
(1) In group 2, the atomic size increases down the group. As the atomic size increases, the nuclear charge decreases. Due to this, electrons of the outermost shell lie further away from the nucleus making the removal of electrons easy. So, Ba will form ions readily.
(2) All the elements have 2 electrons in their valence shell.
ICSE Class 10 Chemistry Question Paper solved Set C
SECTION II (40 Marks)
Attempt any four questions from this Section
(a) Arrange the following as per the instructions given in the brackets:
(i) Cs, Na, Li, K, Rb (increasing order of metallic character).
(ii) Mg, Cl, Na, S, Si (decreasing order of atomic size).
(iii) Na, K, Cl, S, Si (increasing order ionization energy)
(iv) Cl, F, Br, I (increasing order of electron affinity)
(i) Li < Na < K < Rb < Cs (ii) Na > Mg > Si > S > Cl
(iii) K < Na < Si < S < Cl
(iv) I < Br < F < Cl
(b) Choose the most appropriate answer from the following list of oxides which fit the
description. Each answer may be used only once:
[SO2, SiO2, Al2O3, MgO, CO, Na2O]
(i) A basic oxide.
(ii) An oxide which dissolves in water forming an acid.
(iii) An amphoteric oxide.
(iv) A covalent oxide of a metalloid. 
Ans. (i) MgO
(c) Element X is a metal with a valency 2, Y is 3 non-metal with a valency 3.
(i) Write an equation to show how Y from an ion.
(ii) If Y is a diatomic gas, write an equation for the direct combination of X and Y to from a compound.
(i) Y will form an anion by gaining 3 electrons.
The equation is given as Y + 3e– → Y–3.
(ii) The equation for the direct combination of X and Y to form a compound is
3X + Y2 → X3Y2
(a) Give balanced chemical equations for the following conversions:
(i) Ethanoic acid to ethyl ethanoate.
(ii) Calcium carbide to ethyne.
(iii) Sodium ethanoate to methane.
(b) Using their structural formulae identify the functional group by circling them:
(i) Dimethyl ether.
(c) Name the following:
(i) Process by which ethane is obtained from ethene.
(ii) A hydrocarbon which contributes towards the greenhouse effect.
(iii) Distinctive reaction that takes place when ethanol is treated with acetic acid.
(iv) The property of element by virtue of which atoms of the element can link to each other in the form of a long chain or ring structure.
(v) Reaction when an alkyl halide is treated with alcoholic potassium hydroxide. 
Ans. (i) Hydrogenation
(a) Identify the anion present in each of the following compounds:
(i) A salt M on treatment with concentrated sulphuric acid produces a gas which fumes in moist air and gives dense fumes with ammonia.
(ii) A salt D on treatment with dilute sulphuric acid produces a gas which turns lime water milky but has no effect on acidified potassium dichromate solution.
(iii) When barium chloride solution is added to salt solution E a white precipitate insoluble in dilute hydrochloric acid is obtained. 
Ans. (i) Chloride ion (Cl.) (ii) Carbonate ion (CO32.)
(iii) Sulphate ion (SO42.)
(b) The following table shows the tests a student performed on four different aqueous solutions which are X, Y, Z and W. Based on the observations provided, identify the cation present:
Ans. (i) Zn2+
(c) Give balanced chemical equations for each of the following:
(i) Lab preparation of ammonia using an ammonium salt
(ii) Reaction of ammonia with excess chlorine.
(iii) Reaction of ammonia with sulphuric acid. 
Question 5 (a) Consider the following reaction and based on the reaction answer the questions that follow:
(i) the quantity in moles of (NH4)2Cr2O7 if 63gm of(NH4)2Cr2O7 is heated. 
(ii) the quantity in moles of nitrogen formed. 
(iii) the volume in litres or dm3 of N2 evolved at S.T.P. 
(iv) the mass in grams of Cr2O3 formed at the same time. 
(Atomic masses: H=1, Cr= 52, N=14]
Ans. The given reaction is as follows:
Hence, 0.25 moles of (NH4)2Cr2O7 can produce 0.25 moles of nitrogen gas.
The quantity in moles of nitrogen formed is 0.25 moles.
(iii) One mole of an ideal gas at S.T.P. occupies 22.4 litres or dm3.
Hence, 0.25 moles of (NH4)2Cr2O7 will occupy 0.25 × 22.4 = 5.6 litres or dm3.
The volume in litres or dm3 of N2 evolved at S.T.P. is 5.6 litres or dm3.
(iv) From the given chemical equation, 1 mole of (NH4)2Cr2O7 produces 1 mole of Cr2O3.
Hence, 0.25 moles of (NH4)2Cr2O7 will produce 0.25 moles of Cr2O3.
Molar mass of Cr2O3
= (2 × 52) + (3 × 16)
= 104 + 48 = 152 gm
1 mole Cr2O3 = 152 gm
Hence, 0.25 moles of Cr2O3 = 0.25 × 152 = 38 gm
The mass in grams of Cr2O3 formed at the same time is 38 gm.
(b) (i) For each of the substance listed below, describe the role played in the extraction of aluminium.
(2) Sodium hydroxide
(3) Graphite m 6
(ii) Explain why :
(1) In the electrolysis of alumina using the Hall Heroult’s Process the electrolyte is covered with powdered coke.
(2) Iron sheets are coated with zinc during galvanization. 
Ans. (i) In the extraction of aluminium, the given compounds play the following roles:
(1) Cryolite: It lowers the fusion temperature from 2050°C to 950°C and enhances conductivity.
(2) Sodium hydroxide: Two roles are played by sodium hydroxide in the extraction of aluminium.
First, finely grinded bauxite (ore of aluminium) is heated under pressure with conc. caustic soda solution (NaOH solution) for 2–8 hours at 140°C to 150°C to produce sodium aluminate. The chemical equation is as follows:
Al2O3 → 2H2O + 2NaOH → 2NaAlO2 + 3H2O
Second, on diluting sodium aluminate with water and cooling to 50°C, sodium aluminate is hydrolysed to give aluminium hydroxide as precipitate.
Here, the impurities dissolve in sodium hydroxide.
(3) Graphite: Thick rods of graphite are suspended into the fused electrolyte.
They act as an anode where oxygen gas is discharged.
(ii) (1) In the electrolysis of alumina using the Hall–Héroult process, the electrolyte is covered with powdered coke as it reduces heat loss by radiation prevents the burning of the anode
(2) Iron sheets are coated with zinc during galvanisation to prevent them from rusting.
(a) (i) Give balanced chemical equations for the action of sulphuric acid on each of the following:
(1) Potassium hydrogen carbonate. (2) Sulphur.
(ii) In the contact process for the manufacture of sulphuric acid give the equations for the conversion of sulphur trioxide to sulphuric acid. 
Ans. (1) Action of sulphuric acid on potassium hydrogen carbonate
2KHCO3 + H2SO4 → K2SO4 + 2H2O + 2CO2↑
2) Action of sulphuric acid on sulphur
S + 2H2SO4 → 3SO2 + 2H2O
(ii) In the contact process for the manufacture of sulphuric acid, the equations for the conversion of sulphur trioxide to sulphuric acid are
SO3 + H2SO4 (conc.) → H2S2O7 (oleum or pyrosulphuric acid)
H2S2O7 + H2O → 2H2SO4
(c) Explain the following:
(i) Dilute nitric acid is generally considered a typical acid but not so in its reaction with metals.
(ii) Concentrated nitric add appears yellow when it is left standing in a glass bottle.
(iii) An all glass apparatus is used in the laboratory preparation of nitric acid. 
Ans. (i) Dilute nitric acid is generally considered a typical acid but not in its reaction with metals because the action of nitric acid on metals depends on the temperature and concentration of nitric acid. These conditions are not required in case of hydrochloric acid or sulphuric acid.
(ii) Although pure concentrated nitric acid is colourless, it appears yellow when left standing in a glass bottle due to the dissolution of reddish brown nitrogen dioxide gas in the acid. Nitrogen dioxide is produced because of the thermal decomposition of a portion of nitric acid.
4HNO3 ¾¾ → 2H2O + 4NO2 + O2
(iii) An all-glass apparatus is used in the laboratory preparation of nitric acid because nitric acid vapours corrode rubber and cork.
(a) The following questions are pertaining to the laboratory preparation of hydrogen chloride gas:
(i) Write the equation for its preparation mentioning the condition required. 
(ii) Name the drying agent used and justify your choice. 
(iii) State a safety precaution you would take during the preparation of hydrochloric acid. 
ii) The drying agent used in the laboratory preparation of hydrochloric acid is conc.sulphuric acid.
(iii) Funnel arrangement are to be done as HCl is highly soluble in water and to avoid back suction.
Always wear chemical splash goggles, Chemical Resistant Gloves and Chemical Resistant apron in the laboratory during the preperation of Hydrochloric acid.
(b) An element L consists of molecules.
(i) What type of bonding is present in the particles that make up L?
(ii) When L is heated with iron metal, it forms a compound FeL. What chemical term would you use to describe the change undergone by L? 
Ans. (i) Covalent bonding is observed in atoms which are similar. Hence, covalent bonding is present in the particles which make up element L.
(ii) When L is heated with iron metal, it forms a compound FeL.
Here, oxidation of Fe and reduction of L occur as follows:
Fe → Fe2+ + 2e¯
(c) From the list of the following salts choose the salt that most appropriately fits the description given in the following:
[AgCl, MgCl2, NaHSO4, PbCO3, ZnCO3, KNO3, Ca(NO3)2]
(i) A deliquescent salt.
(ii) An insoluble chloride.
(iii) On heating, this salt gives a yellow residue when hot and white when cold.
(iv) On heating this salt, a brown coloured gas is evolved. 
(i) A deliquescent salt = MgCl2
(ii) An insoluble chloride = AgCl
(iii) On heating, this salt gives a yellow residue when hot and a white residue when cold = ZnCO3
(iv) On heating this salt, a brown-coloured gas is evolved = Ca(NO3)2