Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

476.

Which of the following gases contains the least number of atoms at s.t.p?

A.

1 mole of butane

B.

4 moles of chlorine

C.

3 moles of ozone

D.

7 moles of argon

Correct answer is D

4 moles of chlorine gas = 4Cl\(_2\) = 8 atoms of chlorine
3 moles of ozone = 3O\(_3\) = 9 atoms of oxygen
1 mole of butane = C\(_4\)H\(_{10}\)
7 mole of argon = 7Ar = 7 atoms of argon

Argon is a monoatomic noble gas with the least number of atoms.

477.

The IUPAC nomenclature of the compound
H\(_3\)C - CH(CH\(_3\)) - CH(CH\(_3\)) - CH\(_2\) - CH\(_3\)

A.

3,4- dimethylhexane

B.

2,3- dimethyl pentane

C.

2- ethyl hexane

D.

2,3- dimethylhexane

Correct answer is B

No explanation has been provided for this answer.

478.

A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180. Find the molecular formula.
[H = 1, C = 12, O = 16]

A.

C\(_3\)H\(_6\)O\(_3\)

B.

C\(_6\)H\(_6\)O\(_3\)

C.

C\(_6\)H\(_{12}\)O\(_6\)

D.

CH\(_2\)O

Correct answer is C

C → 40/12 ≈ 3

H → 6.7/1 ≈ 6

O → 53.3/16 ≈ 3

dividing through with the lowest value, 3

C\(_1\)H\(_2\)O\(_1\)

[C\(_1\)H\(_2\)O\(_1\)]n = 180

[12 + 2 + 16]m = 180

30n = 180 

n = 6

:C\(_6\)H\(_12\)O\(_6\)

479.

In the reaction:
M + N → P
ΔH = +Q kJ

Which of the following would increase the concentration of the product?

A.

Adding a suitable catalyst

B.

Increasing the concentration of P

C.

Increasing the temperature

D.

Decreasing the temperature

Correct answer is C

No explanation has been provided for this answer.

480.

Sulphur exists in six forms in the solid state. This property is known as

A.

Isomerism

B.

Allotropy

C.

Isotopy

D.

Isomorphism

Correct answer is B

No explanation has been provided for this answer.