Previous Year Paper year:2012 : ICSE-X-Chemistry

with Solutions - page 5

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#3-b

Match the properties and uses of alloys in List 1 with the appropriate answer from List
2.

List 1	List 2
(i) The alloy containing Cu and Zn is hard, silvery and is used in decorative articles.	A. Duralumin
(ii) It is stronger than aluminium, light and is used in making light tools.	B. Brass
(iii) It is lustrous, hard, corrosion resistantand is used in surgical instruments.	C. Bronze
(iv) Tin lowers the melting point of the alloy and is used for soldering purpose.	D. Stainless steel
(v) The alloy is hard, brittle, takes up polishand is used for making statues.	E. Solder

Ans :
(i) (B) Brass
(ii) (A) Duralumin
(iii) (D) Solder
(iv) (D) Stainless steel
(v) (C) Bronze

#4-a-i
i. Compound X on heating with copper turnings and concentrated sulphuric acid
liberates a reddish brown gas.
Ans : ``\ce{NO3^-}`` (Nitrate ion)

#4-a-ii
ii. When a solution of compound Y is treated with silver nitrate solution, a white
precipitate is obtained which is soluble in excess of ammonium hydroxide solution.
Ans : ``\ce{Cl-}`` (Chloride ion)

#4-a-iii
iii. Compound Z which on reacting with dilute sulphuric acid liberates a gas which
turns lime water milky, but the gas has no effect on acidified potassium dichromate
solution.
Ans : ``\ce{CO3^{2-} }``(Carbonate ion)

#4-a-iv
iv. Compound L on reacting with barium chloride solution gives a white precipitate
which is insoluble in dilute hydrochloric acid or dilute nitric acid.
Ans : ``\ce{SO4^{2-} }``(Sulphate ion)

#4-b [3]

State one chemical test between each of the following pairs:

Ans :

1. Test	Sodium Carbonate	Sodium Sulphite
Add dil. HCl or dil. ``\ce{H2SO4}``	Colourless, odourless gas that turn lime water milky but has no effect on acidified potassium dichromate solution is released i.e., ``\ce{CO2}``	Colourless gas with smell of burning sulphur, turn lime water milky and also turn acidified potassium dichromate green is released i.e., ``\ce{SO2}`` gas.
2. Test	Ferrous Nitrate	Lead Nitrate
Add few drops of NaOH	Dirty green ppt of Ferrous hydroxide	Chalky white ppt of lead hydroxide.
3. Test	Manganese dioxide	Copper (II) oxide
Heat with cone. HCl	Greenish yellow gas with irritating smell and acidic nature is released i.e., chlorine gas.	No reaction.

#4-c [10]
Draw an electron dot diagram to show the structure of hydronium ion. State the type of
bonding present in it.
Question 5
Ans :

#5-a-i
i. 67.2 litres of hydrogen combines with 44.8 litres of nitrogen to form ammonia under specific conditions as
$$\ce{ N2(g) + 3H2(g) -> 2NH3(g)}$$
Calculate the volume of ammonia produced. What is the other substance, if any,
which remains in the resultant mixture?

#5-a-ii
ii. The mass of ``\pu{5.6 dm324 g }`` of a certain gas at STP is ``\pu{12.0 g}``. Calculate the relative molecular
mass of the gas.