JAMB Chemistry Past Questions & Answers - Page 41

201.

Which of the following factors will speed up the rate of evolution of carbon (iv) oxide in the reaction below?
2HCl + CaCO\(_3\) → CaCl\(_2\) + H\(_2\)O + CO\(_2\)

A.

Increasing the concentration of the acid

B.

Increasing the surface area of CaCO\(_3\)

C.

A and B

D.

Reducing the concentration of the acid

Correct answer is C

The following factors increase a reaction rate
- Increase in concentration of reactants
- Increase in temperature
- Addition of catalyst
- Increase in the surface area of reactant(s)

202.

The part of the total energy of a system that accounts for the useful work done in a system is known as

A.

Enthalpy change

B.

None of the above

C.

Gibb's free energy

D.

Entropy

Correct answer is C

Gibb's free energy is the fraction of the total energy of a system that accounts for how much useful work can be done in a system.

203.

When the end alkyl groups of ethyl ethanoate are interchanged, the compound formed is

A.

propylmethanoate

B.

ethylpropanoate

C.

methyl ethanoate

D.

methyl propanoate

Correct answer is D

No explanation has been provided for this answer.

204.

An element Z contains 80% of \(^{16} _8\)Z and 20% of \(^{18} _8\)Z. Its relative atomic mass is

A.

16.2

B.

17.6

C.

16.0

D.

16.4

Correct answer is D

R.A.M of Z = \(16(\frac{80}{100}) + 18(\frac{20}{100})\)

= \(12.8 + 3.6\)

= 16.4

205.

How many electrons will be found in the nucleus of an atom with mass number 23 and 17 neutrons?

A.

none

B.

6

C.

7

D.

8

Correct answer is A

Electrons are found in the orbit of the atom. They revolve around the nucleus. There's no electron found in the nucleus of an atom.