Previous Year Paper year:2017 : ICSE-X-Chemistry

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ICSE-X-Chemistry

Previous Year Paper year:2017

with Solutions - page 2

#1-c-v
A solid formed by reaction of two gases, one of which is acidic and the other basic
in nature.
Ans : Salt

#1-d [5]
Write a balanced chemical equation for each of the following:

#1-d-i
Action of cold and dilute Nitric acid on Copper.
Ans : ``\ce{3Cu + 8HNO3 -> 3Cu(NO3)2 + 4H2O + 2NO(^)}``

#1-d-ii
Reaction of Ammonia with heated copper oxide.
Ans : ``\ce{3CuO + 3NH3 -> 3Cu + 3H2O + N2(^)}``

#1-d-iii
Preparation of methane from iodomethane.
Ans : ``\ce{CH3I + 2[H] -> CH4 + HI}``

#1-d-iv
Action of concentrated sulphuric acid on Sulphur.
Ans : ``\ce{S + 2H2SO4 -> 3SO2 + 2H2O}``

#1-d-v
Laboratory preparation of ammonia from ammonium chloride.
Ans : ``\ce{2NH4Cl + Ca(OH)2 -> CaCl2 + 2H2O + 2NH3(^)}``

#1-e [5]
State one relevant observation for each of the following reactions:

#1-e-i
Addition of ethyl alcohol to acetic acid in the presence of concentrated Sulphuric
acid.
Ans : Sweet smelling ethyl acetate ester is
produced, and the process is known as esterification.
``\ce{C2H5OH + CH3COOH -> CH3COOC2H5 + H2O}``

#1-e-ii
Action of dilute Hydrochloric acid on iron (II) sulphide.
Ans : hydrogen sulphide having rotten egg smell.
``\ce{FeS + 2HCl -> FeCl2 + H2S}``

#1-e-iii
Action of Sodium hydroxide solution on ferrous sulphate solution.
Ans : dirty green gelatinous ppt. of ferrous hydroxide is formed along with colourless
sodium sulphate.
``\ce{FeSO4 + 2NaOH -> Fe(OH)2. + Na2SO4}``

#1-e-iv
Burning of ammonia in air.
Ans : it extinguishes a burning splint and does not burn in air.

#1-e-v
Action of concentrated Sulphuric acid on hydrated copper sulphate.
Ans : Concentrated sulphuric acid removes water of crystallisation from
blue-coloured hydrated copper sulphate to form white anhydrous
copper sulphate.
``\ce{CuSO4.5H2O->CuSO4 +5H2O}``
Blue --- Dirty white

#1-f [5]
(i) Draw the structural formula for each of the following:
1. 2, 3 . dimethyl butane
2. Diethyl ether
3. Propanoic acid
Ans :
(i)
1. 2, 3-dimethyl butane

2. diethyl ether

3. propanoic acid

#1-f-ii
Select the process from the following which matches the given description.
(calcination, roasting, pulverisation, smelting)
1. Crushing of the ore into a fine powder.
2. Heating of the ore in the absence of air to a high temperature.
Ans : 1. The process of crushing ores into a fine powder in big crushers and
ball mills is known as pulverisation.
2. Heating of the ore in the absence of air to a high temperature that
is high but insufficient to melt the ore is known as calcination.