Waec Chemistry 1989 Past Questions and Answers

Question 21:

• WAEC 1989

Given the following half-cell reaction; 2Cl_(aq) → CI_2(g) + 2e, how many mole of electrons will be required to produce 1.12dm³ of chlorine gas at s.t.p? (Molar volume of a gas at s.t.p. = 22.4dm ³)

A. 1.00
B. 0.40
C. 0.20
D. 0.10
E. 0.01

Question 22:

• WAEC 1989

Which of the following is used extensively in manufacturing photographic chemicals?

A. Aluminium chloride
B. Zinc chloride
C. Silver chloride
D. Mercury (ll) chloride
E. Lron (ll) chloride

Question 23:

• WAEC 1989

Given that 1 mole of carbon -12 weighs 12.0g, how many atoms are there in 24.0g magnesium? (C = 12, Mg = 24, NA = 6.02 x 10 ²³mol^-1)

A. 1/2 x 6.02 x 10 ²³
B. 1 x 6.02 x10 ²³
C. 2 x 6.02 x 10 ²³
D. 3x 6.02 x 10 ²³
E. 4x 6.02 x 10 ²³

Question 24:

• WAEC 1989

What is the concentration, in mol dm ³, of solution is allowed to evaporate the allotrope of sulphur formed is

A. Plastic sulphur
B. Amorphous sulphur
C. Rhombic sulphur
D. Monoclinc sulphur
E. Colloidal sulphur

Question 25:

• WAEC 1989

If sulphur is dissolved in carbon (IV) sulphide and the solution is allowed to evaporate, the allotrope of sulphur formed is

A. Plastic sulphur
B. Amorphous sulphur
C. Rhombic sulphur
D. Monoclinc sulphur
E. Colloidal sulphur