Waec Chemistry 2000 Past Questions and Answers

Question 26:

• WAEC 2000

What is the value of x in the following equation? Cr₂O₇^2- + 14H⁺ + xe- → 2Cr³⁺ + 7H₂O

A. 1
B. 6
C. 8
D. 12

Question 27:

• WAEC 2000

In which of the following is the oxidation number of sulphur equal to -2?

A. S₈
B. H₂S
C. SO ₂
D. SO ₃^2-

Question 28:

• WAEC 2000

An iron nail placed in a solution copper (ll) tetraoxosulphate (VI) is soon covered with a deposit of copper which of the following equations represents the reactions ?

A. Fe ²⁺_(aq) + Cu_(s) → Fe ³⁺ + Cu ²⁺_(aq)
B. Fe ²⁺_(aq) + Cu_(s) → Fe_(s) + Cu²⁺_(aq)
C. Fe _(s) + Cu²⁺_(aq) → Fe²⁺_(aq) + Cu²⁺_(aq)
D. Fe_(s) + Cu²⁺ → Fe²⁺_(aq) + Cu_(s)

Question 29:

• WAEC 2000

0.10 mol dm^-3 NaCI conducts electricity better than 0.10 mol dm^-3 CH₃COOH because the solution of NaCI

A. Contains more ions
B. Is neutral to litmus
C. Has a lower molar mass
D. Has a higher pH

Question 30:

• WAEC 2000

Which of the following occurs when a solution of CuSO₄/> is electrolysed using copper electrodes?

A. The cathode becomes coated with copper
B. Both electrodes gain electrons
C. The blue colour of the solution fades gradually
D. The anode increases in mass