Jamb Chemistry Past Questions and Answers

Question 116:

• JAMB 1979

The oxidation state of manganese in potassium permanganate is

A. +7
B. +5
C. +3
D. +2
E. +1

Question 117:

• JAMB 1979

When carbondioxide is bubbled into limewater a white precipitate is formed. If the passage of the gas is continued, the precipitate disappears. The reason for this is

A. Calcium carbonate is formed which on reaction dissolves
B. Calcium hydrogen carbonate is precipitated and then dissolves
C. Calcium carbonate is formed which on reaction with further carbondioxide forms solube calcium hydrogen carbonate
D. Concentration of the solution has occurred with the deposition of calcium hydroxide
E. The solution has become saturated and solid carbondioxide has been deposited

Question 118:

• JAMB 1979

Methanoic acid mixes with water in all proportions and has about the same boiling point as water which of the following methods would you adopt to obtain pure water from a mixture of stand, water and methanoic acid?

A. Fractional distillation
B. Filtration followed by distillation
C. Neutralization with sodium hydroxide followed by distillation
D. Esterification with ethanol followed by distillation
E. Neutralization with sodium hydroxide followed by filtration

Question 119:

• JAMB 1979

Which of the following statements applies during the electroysis of sodium hydroxide sodium hydroxide solution using platinum electrodes?

A. Na⁺ ions are discharged at the cathode
B. Hydrogen ions are discharged at the anode
C. The concentration of sodium hydroxide decrease at both electrode compartments
D. The concentration of sodium hydroxide increases at the cathode only
E. The concentration of sodium hydroxide increases at the anode only

Question 120:

• JAMB 1979

Which of the following statements is true? When the potassium atom forms its ion

A. It gains one electron and becomes neutral
B. Its atomic number decreases
C. It achieves electronic configuration of orgon
D. It loses one proton
E. It loses one neutron