Waec Chemistry 1991 Past Questions and Answers

Question 21:

• WAEC 1991

The ratio of reactants to products is 1: 3: 2 in the reaction represented by the equation below: N_{2,/SUB> [sub](g)} → 2NH_3(g) which of the following law is demonstrated by this?
[/sub]

A. Boyle's law
B. Law of multiple proportion
C. Gay Lussac's law
D. Law of constant composition
E. Avogadro's law

Question 22:

• WAEC 1991

In the redox reaction represented by the following equation: Cu^{2+_aq + Zn_(s) → Cu_(s) + Zn[sup]2+}[/sup]

A. The oxidation number of copper increases
B. Copper (ll) ions are reduced to copper atoms
C. Zinc atoms are reduced to zinc ions
D. Copper (ll) ions donate electrons to zinc atoms

Question 23:

• WAEC 1991

When starch undergoes complete enzyme-catalyzed hydrolysis, the resulting product is

A. Glucose
B. Maltose
C. Sucrose
D. Fructose
E. Cellulose

Question 24:

• WAEC 1991

Which of the reactions represented by the following equations will take place at room temperature?

A. C 6 H₂O → CO + H₂
B. CuO + H₂ → Cu + H₂O
C. N₂ + 3H₂ → 2NH₃
D. 2Na + 2H₂O → 2NaOH + H₂
E. 2Fe + 3CI₂ → 2FeCI₃

Question 25:

• WAEC 1991

Which of the following is not a direct petroleum product?

A. Methane
B. Ethanol
C. Petrol
D. Vaseline
E. Kerosene