ICSE Board Class X Chemistry Board Paper 2013 Solution SECTION I

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1 ICSE Board Class X Chemistry Board Paper 2013 Solution SECTION I 1) i. Hydronium ii. Hydroxide iii. Salt iv. Water v. Hydrogen 2) i. C 2 H 6 gas Reaction: ii. Sulphur dioxide gas is evolved. K 2 SO 3 + 2HCl 2KCl + SO 2 + H 2 O iii. Nitrogen dioxide gas is evolved. S + 6HNO 3 H 2 SO 4 + 2H 2 O + 6NO 2 iv. Oxygen is evolved. 2KNO 3 2KNO 2 + O2 v. Chlorine gas MnO 2 + 4HCl MnCl 2 + 2H 2 O + Cl 2 3) i. Blue-coloured hydrated copper sulphate becomes white anhydrous copper sulphate. Its water of crystallisation is removed. ii. Hydrogen sulphide gas is evolved which has rotten egg smell. iii. Hydrogen chloride and yellow-coloured explosive liquid nitrogen trichloride are produced. iv. A white precipitate of silver chloride is formed which is soluble in ammonium hydroxide. v. Dark reddish brown fumes of bromine evolve at the anode and greyish white metal lead is formed on the cathode. 4. Coordinate bond 5.Acidic salt

2 6. Halogenation 7. Water of crystallisation 8. Deliquescence 9. i. Add silver nitrate solution to both the solutions. Sodium chloride will form curdy white ppt., whereas sodium nitrate will not undergo any reaction. ii. Hydrogen chloride gas gives thick white fumes of ammonium chloride when glass rod dipped in ammonia solution is held near the vapours of the acid, whereas no white fumes are observed in case of hydrogen sulphide gas. iii. Ethene gas decolourises the purple colour of KMnO 4, whereas ethane does not decolourise KMnO 4 solution. iv. Calcium nitrate forms no ppt. even with addition of excess of NH 4 OH, whereas zinc nitrate forms a white gelatinous ppt. which dissolves in excess of NH 4 OH. v. Carbon dioxide gas has no effect on acidified KMnO 4 or K 2 Cr 2 O 7, but sulphur dioxide turns potassium permanganate from pink to colourless. 10) D 11) B 12) C 13) A 14) A 15) C 16) B 17) B 18) C 19) C 20) i. 2V 13V 2 vols. of butane requires O 2 = 13 vols. So, 90 dm 3 of butane will require O 2 = 13 90= 585dm 2 ii. Molecular mass = 2 vapour density. So, molecular mass of gas = 2 8 = 16 g As we know, molecular mass or molar mass occupies 22.4 litres. i.e. 16 g of gas occupies volume = 22.4 litres So, 24 g of gas will occupy volume = =33.6 litres. 16 iii. According to Avogadro's law, equal volumes of all gases under similar conditions of temperature and pressure contain the same number of molecules. So, molecules of nitrogen gas present in the same vessel = X

3 SECTION II 21. Periodic table: (a) i. J ii. R iii. M iv. 5 v. T vi. Y vii. Ionic bond will be formed and the molecular formula is A 2 H. (22) Sodium chloride is soluble in water, whereas carbon tetrachloride is insoluble in water. Sodium chloride being an ionic compound allows electricity to pass through it and is an electrical conductor, whereas carbon tetrachloride being a covalent compound does not conduct electricity. (23) Chemical equations: i. Sodium sulphate: ii. Zinc carbonate: iii. Copper (II) sulphate: iv. Iron (II) sulphate: (24) Observations: i. When ammonium hydroxide is added to copper nitrate, a pale blue ppt. of copper hydroxide is formed. The ppt. dissolves on addition of excess of NH 4 OH and forms blue-coloured solution of tetrammine copper (II) sulphate.

4 ii. When ammonium hydroxide is added to zinc nitrate, a white gelatinous ppt. of zinc hydroxide is formed. The ppt. dissolves on addition of excess of NH 4 OH and forms colourless solution of tetrammine zinc (II) sulphate. iii. Lead nitrate decrepitates on heating; a yellow solid is formed and it fuses with glass. Lead nitrate decomposes into lead oxide, nitrogen dioxide and oxygen. (25) i. The right electrode is the anode and oxidising electrode. Cu Cu e losing electrode. ii. Reaction at anode: Cu Cu e Reaction at cathode: Cu e Cu iii. The anode dissolves and anode mud containing precious metal is recovered. (26) i. Y ii. 3 iii. Acidic; basic iv. Poor v. Lose; reducing (27) Equations: i ii iii (a) Name of the process: Haber's process Temperature: C Catalyst: Finely divided iron with aluminium oxide or a little amount of molybdenum 28) Extraction of aluminium: i. Cryolite (Na 3 AlF 6 ) is added along with alumina and fluorspar. It lowers fusion temperature from 2050 C to 950 C and enhances conductivity. ii. Al e Al iii. It is necessary to renew the anode periodically as it gets oxidised by oxygen evolved at the anode.

5 29) Equations: (b) Structural formulae: i. Isomer of n-butane: Iso-butane ii. 2-propanol iii. Diethyl ether (c) Reasons: i. Alkanes are saturated, i.e. they do not have a carbon-to-carbon double bond, and so do not undergo addition reaction. Alkenes are said to be unsaturated because of the carbon-to-carbon double bond in their structure, and the double bond in alkenes makes them more reactive than alkanes.

6 ii. Ethyne is a highly reactive compound due to the presence of a triple bond between its two carbon atoms. iii. Hydrocarbons are used as fuels because they burn in air producing a lot of heat energy. 30) 3 vols. of oxygen require KClO 3 = 2 vols. So, 1 vol. of oxygen will require KClO 3 = 2 3 vols. So, 6.72 litres of oxygen will require KClO 2 3 x 6.72=4.48 litres litres of KClO 3 has mass = g So, 4.48 litres of KClO 3 will have mass = x4.48=24.5g 22.4 ii litres of oxygen = 1 mole So, 6.72 litres of oxygen = 6.72 =0.3 moles 22.4 No. of molecules present in 1 mole of O 2 = So, no. of molecules present in 0.3 mole of O2 = = iii. Volume occupied by 1 mole of CO 2 at STP = 22.4 litres So, volume occupied by 0.01 mole of CO 2 at STP = = litres (31) i. Ammonia gas ii. Acetic acid iii. Hydrogen chloride iv. Sulphuric acid v. Helium

ICSE Board. Class X Chemistry. Board Paper Time: 1½ hrs Total Marks: 80

ICSE Board. Class X Chemistry. Board Paper Time: 1½ hrs Total Marks: 80 ICSE Board Class X Chemistry Board Paper 2013 Time: 1½ hrs Total Marks: 80 General Instructions: 1. Answers to this paper must be written on the paper provided separately. 2. You will NOT be allowed to