Jamb Chemistry Past Questions and Answers

Question 696:

• JAMB 1991

If a current of 1.5 A is passed for 4.00 hours through a molten tin salt and 13.3g of tin is deposited, what is the oxidation state of the metal in the salt?
(Sn = 118.7, F = 96500 C mol^-1)

A. 1
B. 2
C. 3
D. 4

Question 697:

• JAMB 1991

Which of the following equimolar solutions, Na₂CO₃ Na₂ SO₄CI FeCI₃ CH₃COONa,
have pH greater than 7?

A. FeCI ₃ and NH ₄CI
B. Na₂CO₃, CH₃COONa and Na,Na₂SO₄
C. Na₂CO₃ and CH₃COONa
D. FeCI₃, CH₃COONa and NH₄CI

Question 698:

• JAMB 1991

MnO^-₄ + 8H⁺ + ne → Mn⁺⁺ + 4H₂O. Which is the value of n in the reaction above?

A. 2
B. 3
C. 4
D. 5

Question 699:

• JAMB 1991

2H2S(g) + SO2(g) → 3S(s) + 2H2O(I). The above reaction is?

A. A redox reaction H₂S is the oxidant and SO₂ is the reductant
B. A redox reaction in which SO₂ is the oxidant and H₂S is the reductant
C. Not a redox reaction because there is no oxidant in reaction equation
D. Not a redox because there is no reductant in the reaction equation

Question 700:

• JAMB 1991

Magnesium (IV) oxide is known to hasten the decomposition of hydrogen peroxide. Its main action is to?

A. Increase the surface area of the reactants
B. Increase the concntration of the reactants
C. Lower the activation energy for the reaction
D. Lower the heat of reaction, ∆H, for the reaction