Waec Chemistry 1992 Past Questions and Answers

Question 41:

• WAEC 1992

(a) Name the crystalline allotrope of sulphur that is stable at room temperature.
(b)(i) Give one example of a fuel that contains significant amount of sulphur as an impurity.
(ii) State one environmental disadvantage of using a fuel that has high sulphur content

Question 42:

• WAEC 1992

(a) Give the electrolyte of a named secondary electrochemical cell.
(b) Consider the cell represented as shown below: \(Cu_{(s)}Cu^{2+}_{(aq)}/Zn^{2+}_{(aq)}/Zn{(s)}\)
(i) What does the vertical double stroke represent?
(ii) Which of the metals forms the cathode?
(iii) Name the electrode to which each half-cell should be coupled if the oxidation potential of the half-cells are to be determined.

Question 43:

• WAEC 1992

Magnesium ribbon reacts with dilute hydrochloric acid at room temperature.
(a) State three ways by which the reaction can be made to proceed faster
(b) Write an equation for the reaction.

Question 44:

• WAEC 1992

(a) Give one example of naturally-occurring acids
(b) If 0.5 mole of a mono-alkanoic acid weighs 44g, determine the molecular formula and the name of the acid. (H = 1, C = 12, O = 16)

Question 45:

• WAEC 1992

(a) Three elements A, B and C have atomic numbers 8, 11 and 12 respectively.
(i) Write the formula of the compound formed by the chemical combination of A and B.
(ii) State which of the three elements belong(s) to the s-block of the Periodic Table. Give reason for your answer:
(b) List the component elements of bleaching powder.