JAMB Chemistry Past Questions & Answers - Page 25

121.

The sub-atomic particles located in the nucleus of an atom are?

A.

neutron and proton

B.

proton and electron

C.

proton and ions

D.

neutron and electron

Correct answer is A

The nucleus contains two types of subatomic particles, protons and neutrons.

The protons have a positive electrical charge and the neutrons have no electrical charge.

A third type of subatomic particle, electrons, move around the nucleus.

122.

If humid air is polluted by chlorine discharged, the air can be restored by sprinkling

A.

solid MnO\(_{2}\)

B.

acidified KMnO\(_{4}\)

C.

acidified FeSO\(_{4}\)

D.

saturated NaCl(aq)

Correct answer is B

Chlorine is a toxic gas and when it pollutes the air, it can be neutralized by using acidified KMnO4. The reaction between chlorine and acidified KMnO4 results in the formation of chloride ions, manganese(II) ions, and water, which are harmless. This is why acidified KMnO4 is used to restore air polluted by chlorine discharge.

123.

Cathodic protection of metals is based on

A.

standard electrode potential of hydrogen

B.

its electrical conductivity

C.

nature of oxides formed

D.

relative tendencies of oxidation

Correct answer is D

No explanation has been provided for this answer.

124.

What is the relative molecular mass of the compound below?

[H = 1.0; C = 12.0; O = 16.0]

A.

137

B.

136

C.

64

D.

59

Correct answer is B

The molecular formula of the compound in question is \(C_6H_5COOCH_3\)

Then its relative molecular mass = 8C + 8H + 2O = 8 X 12 + 8 x 1 + 2 X 16 = 136

125.

The ratio of carbon atoms of hydrogen atoms in a hydrocarbon is 1:2. If its molecular mass is 56, what is its molecular formula?

A.

C\(_{3}\)H\(_{6}\)

B.

C\(_{4}\)H\(_{8}\)

C.

C\(_{2}\)H\(_{4}\)

D.

CH\(_{2}\)

Correct answer is B

No explanation has been provided for this answer.