Waec Chemistry 2003 Past Questions and Answers

Question 21:

• WAEC 2003

Which of the following statements is/are correct about tin plating? l The electrolyte must be a soluble salt of tin ll. the objective to be plated is made the cathode lll. The anode is made of tin lV. The negative electrode dissolves

A. L only
B. L and ll only
C. L,ll and lll only
D. L, ll and lV only

Question 22:

• WAEC 2003

Determine the amount of electrons needed to deposit 6.4g of copper during the electrolysis of copper (ll) tetraoxosulphate (IV) solution [Cu = 64]

A. 0.10 mole
B. 0.20 mole
C. 1.0 mole
D. 2.0 mole

Question 23:

• WAEC 2003

A given fuel has an octane number of 100. This means that

A. The knocking tendency of the fuel is low
B. The fuel is a mixture of several hydrocarbons
C. A large amount of alkanes is present in the fuel
D. The fuel needs to be cracked before use

Question 24:

• WAEC 2003

The equation for the reaction at the anode during the electrolysis of concentrated sodium chloride solution is

A. 2CI^-_(aq) → CI,sub>2(g) + 2e^-
B. 40H^-_(aq) → 2H₂O_(I) + O_2(g) + 4e ^-
C. Na⁺_(aq) + e^- → Na_(s)
D. 2H⁺_(aq) + 2e^- → H_2(g)

Question 25:

• WAEC 2003

Which of the following compounds has the same empirical formula as benzene?

A. C₂H₂
B. C₂H₄
C. C₄H₆
D. C₆H₁₂