Waec Chemistry Past Questions For Year 2016

Question 36

Which of the following salts when dissolved in water will form a solution that will change blue litmus to red?

waec 2016

• A. CH₃COONa
• B. NH₄Cl
• C. NaCl
• D. KCl

Question 37

Amino acids are obtained from proteins by

waec 2016

• A. Hydrolysis
• B. Oxidation
• C. Polymerization
• D. Reduction

Question 38

Consider the following half-cell reactions.

Al_(s) \(\to\) Al³⁺_(aq) + 3e^-

Cu²⁺_(aq) + 2e^- \(\to\) Cu_(s)

The overall equation for the reaction is

waec 2016

• A. Al_(s) + Cu²⁺_(aq) \(\to\) Al³⁺_(aq) + Cu_(s)
• B. 2Al_(s) + Cu²⁺_(aq) \(\to\) 2Al_(aq) + Cu_(s)
• C. 2Al_(s) + 3Cu²⁺_(aq) \(\to\) 3Cu_(s) + 2Al³⁺_(aq)
• D. 3Al_(s) + 2Cu²⁺_(aq) \(\to\) Cu_(s) + 3Al³⁺_(aq)

Question 39

Consider the following ionic equation:

Cr₂O₇^2- + 14H⁺ + ne^- \(\to\) 2Cr³⁺ + 7H₂O.

The value of n in the equation is_______?

waec 2016

• A. 7
• B. 6
• C. 3
• D. 2

Question 40

The oxidation number of sulphur is +4 in

waec 2016

• A. Na₂S>₂O₃
• B. H₂SO₃
• C. H₂SO₄
• D. SO₃