Oxidation and reduction - Jamb Chemistry Past Questions and Answers

Question 101:

• JAMB 2018

In electrovalency, the oxidation number of the participating metal is always

A. Decreasing
B. Increasing
C. Constant
D. Neutral

Question 102:

• JAMB 2019

Which of the following reactions is an oxidation process?

A. 2H\(^+\) + 2e\(^-\) \(\to\) H\(_2\)
B. 2O\(^{2-}\) + 4e\(^-\) \(\to\) O\(_2\)
C. OCl\(^-\) + H\(_2\)O + 2e\(^-\) \(\to\) 2OH\(^-\) + Cl\(^-\)
D. Cl + e\(^-\) \(\to\) Cl\(^-\)

Question 103:

• JAMB 2019

If acidified Potassium Dichromate(VI) (K\(_2\)Cr\(_2\)O\(_7\)) acts as oxidizing agent, color changes from

A. Yellow to green
B. Orange to green
C. Yellow to red
D. Orange to red

Question 104:

• JAMB 2019

Consider the equation below:
Cr\(_2\)O\(_7 ^{2-}\) + 6Fe\(^{2+}\) + 14H\(^{+}\) \(\to\) 2Cr\(^{3+}\) + 6Fe\(^{3+}\) + 7H\(_2\)O.
The oxidation number of chromium changes from

A. +5 to +3
B. +6 to +3
C. -2 to +3
D. +7 to +3

Question 105:

• JAMB 2019

The oxidation state(s) of nitrogen in ammonium nitrite is/are

A. -3, +3
B. +5
C. -3, +5
D. -3