ICSE Board
Class X Chemistry
Board Paper – 2013 Solution
SECTION I
1)
i. Hydronium
ii. Hydroxide
iii. Salt
iv. Water
v. Hydrogen
2)
i. C2H6 gas
Reaction:
ii.
Sulphur dioxide gas is evolved.
K2SO3 + 2HCl → 2KCl + SO2 + H2O
iii. Nitrogen dioxide gas is evolved.
S + 6HNO3 →H2SO4 + 2H2O + 6NO2
iv. Oxygen is evolved.
2KNO3 → 2KNO2 + O2
v. Chlorine gas
MnO2 + 4HCl →MnCl2 + 2H2O + Cl2
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
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 KMnO4, whereas ethane does not decolourise
KMnO4 solution.
iv. Calcium nitrate forms no ppt. even with addition of excess of NH4OH, whereas zinc nitrate
forms a white gelatinous ppt. which dissolves in excess of NH4OH.
v. Carbon dioxide gas has no effect on acidified KMnO4 or K2Cr2O7, 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 O2 = 13 vols.
13
So, 90 dm3 of butane will require O2 = 2 ×90= 585dm
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
22.4
So, 24 g of gas will occupy volume = 16 ×24=33.6 litres.
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
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 A2H.
(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 NH4OH and forms blue-coloured
solution of tetrammine copper (II) sulphate.
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 NH4OH 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.
ii.
iii.
The right electrode is the anode and oxidising electrode. Cu → Cu2+ + 2e− losing electrode.
Reaction at anode: Cu → Cu2+ + 2e−
Reaction at cathode: Cu2+ + 2e− →Cu
The anode dissolves and anode mud containing precious metal is recovered.
(26)
i.
ii.
iii.
iv.
v.
Y
3
Acidic; basic
Poor
Lose; reducing
(27)
Equations:
i
ii
iii
(a) Name of the process: Haber's process
Temperature: 450–500°C
Catalyst: Finely divided iron with aluminium oxide or a little amount of molybdenum
28) Extraction of aluminium:
i.
Cryolite (Na3AlF6) is added along with alumina and fluorspar. It lowers fusion
temperature from 2050°C to 950°C and enhances conductivity.
ii.
Al3+ + 3e−
Al
iii.
It is necessary to renew the anode periodically as it gets oxidised by oxygen evolved at
the anode.
29) Equations:
(b) Structural formulae:
i.
Isomer of n-butane: Iso-butane
ii.
iii.
2-propanol
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.
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 KClO3 = 2 vols.
2
So, 1 vol. of oxygen will require KClO3 = 3 vols.
2
So, 6.72 litres of oxygen will require KClO3 x 6.72=4.48 litres
3
22.4 litres of KClO3 has mass = 122.5 g
122.5
So, 4.48 litres of KClO3 will have mass = 22.4 x4.48=24.5g
ii. 22.4 litres of oxygen = 1 mole
6.72
So, 6.72 litres of oxygen = =0.3 moles
22.4
No. of molecules present in 1 mole of O2 = 6.023 × 1023
So, no. of molecules present in 0.3 mole of O2 = 6.023 × 1023 × 0.3 = 1.8061023
iii. Volume occupied by 1 mole of CO2 at STP = 22.4 litres
So, volume occupied by 0.01 mole of CO2 at STP = 22.4 × 0.01= 0.224 litres
(31)
i.
ii.
iii.
iv.
v.
Ammonia gas
Acetic acid
Hydrogen chloride
Sulphuric acid
Helium