### Chemistry Past Questions

4116

(a)i. With the aid of an equation, explain briefly why aluminum metal is not affected by air.

(ii) In the extraction of aluminum from bauxite, state the:
- substance used for purifying the ore;
- composition of the mixture electrolyzed.

(b) ZnO is an amphoteric oxide. Write equations to illustrate this statement.

(c)i) List three uses of sodium trioxocarbonate(IV).

(ii) Explain briefly why a solution of trioxonitrate(V) acid turns yellowish on storage for some time.

(ii) Describe briefly how trioxonitrate(V) ions could be tested for in the laboratory.

(d) Write balanced chemical equations for the preparation of hydrogen chloride.

(i) using concentrated H$$_{2}$$SO$$_{4}$$:

(ii) by direct combination of its constituent elements.

(iii) State one use of hydrogen chloride.

WAEC 2021