ICSE CHEMISTRY - PRACTICE PAPER 16

ICSE CHEMISTRY - PRACTICE PAPER 16

Question 1                                                                                                                            4+4+2

a)      Give reason:

i) In the extraction of Aluminium from Bauxite further refining is not reqired.

ii) Aluminium oxide is reduced by electrolysis but not using reducing agents.

iii) Aluminium powder is used in paints.

iv) Zinc is used in the alloys like Bronze and Brass.

b)      i) Carbon is added to Iron in to impart _______(hardness/lustre).

ii) The substance added to the ore to get rid of impuries  is called ______Matrix/Flux.

iii) In thermite welding Aluminium acts as a/an ________ oxidizing /reducing agent.

iv) Metals _______lose/gain electrons and form cations.

c)      Give balanced equations for the conversion of Lead sulphate to Lead carbonate.(in 2 steps)

Question 2                                                                                                                             3+3+4

Answer the following questions regarding the extraction of Aluminium from Bauxite ore.

a) i) State the formula of Bauxite ore.

ii) Which property of Bauxite makes it react with Sodium hydroxide.

iii)The process adding Aluminium hydroxide crystals to dil. Sodium aluminate to precipitate out Al(OH)₃ is called seeding/smelting.

b) i) Mention any one difficulty faced during the electrolysis of Alumina.

ii) State the composition of the electrolyte taken the Hall Heroult’s process.

iii) Give one advantage of adding Cryolite to alumina in the above process.

c) i)Give reason why Graphite electrodes are replaced continuously in this process.

ii) What are the precautions to be taken to prevent the heat loss during the process.

iii) Give balanced equation for the electrolytic reaction that takes place at cathode.

iv) Name the products formed at anode other than Oxygen.