The following questions are pertaining to the laboratory preparation of Ammonia gas.

(a) Write a balanced chemical equation for its preparation mentioning the conditions required.

(b) Why is a higher ratio by weight of the alkali used?

(c) How is Ammonia gas collected?

Name a probable cation present based on the following observations:

(a) Green precipitate insoluble in Ammonium Hydroxide.

(b) Gelatinous white precipitate soluble in excess of NaOH solution

What do you see in each of the following reactions:

(a) When excess Ammonia gas is passed through an aqueous solution of Zinc Nitrate.

(b) Copper Sulphate crystals are heated strongly.

(c) Sodium hydroxide is added to Copper Sulphate solution in excess.

The following is a sketch of an electrolytic cell used in the extraction of aluminium :

(i) What is the substance of which the electrodes A and B are made?

(ii) At which electrode (A or B) is the aluminium formed ?

(iii) What are the two aluminium compounds in the electrolyte C ?

(iv) Why is it necessary for electrode B to be continuously replaced ?