Waec Chemistry 1989 Past Questions and Answers

Question 36:

• WAEC 1989

(a) When is a sample of water said to be hard?
(b) State one difference between temporary and permanent hardness of water
(c) Give one method of removing hardness completely from water
(d) Name two local is used for the production of soap.

Question 37:

• WAEC 1989

(a) Give one physical property of
(i) diamond;
(ii) graphite
(b) Give two uses of diamond
(c) evidence that shows that both graphite and diamond are allotropes of carbon.

Question 38:

• WAEC 1989

(a) Give two characteristic features of boiling
(b) What will be the effect of the following on the boiling point of water:
(i) addition of crystals of sodium chloride,
(ii) reduction of the atmospheric pressure?
(c) State two ways in which boiling differs from evaporation.

Question 39:

• WAEC 1989

(a) Write the formula of the oxide of nitrogen in which nitrogen has oxidation number of (i) +1;
(ii) +2;
(iii) +3;
(iv) +4;
(b) State which of the oxides in (a) above is/are: (i) acidic (ii) neutral.

Question 40:

• WAEC 1989

Name the type of chemical process involved in the production of
(a) polythene from ethene
(b) ethene from kerosene fraction of petroleum.
(c) soap from vegetable oils
(d) margarine from vegetable oils