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.

2,096.

The following are s-block elements except

A.

lithium

B.

magnesium

C.

potassium

D.

calcium

E.

aluminium

Correct answer is E

No explanation has been provided for this answer.

2,097.

Given that for the reaction. N2(g) + 3H2(g) ⇌ 2NH3(g) ∆H = -92kJ. What is the enthalpy of formation of ammonia from its elements?

A.

-46KJ mol -1

B.

-184KJmol -1

C.

-92KJmol -1

D.

184KJmol -1

E.

+46KJmol -1

Correct answer is A

In the reaction the enthalpy of formation 2 mole of NH3 is - 92kJ. Therefore the standard \(\Delta H\) of formation = \(\frac{-92kJ}{2} = -46KJmol^{-1}\).

2,098.

If sulphur is dissolved in carbon (IV) sulphide and  the solution allowed to evaporate the allotrope of sulphur formed is

A.

plastic sulphur

B.

amorphous sulphur

C.

rhombic sulphur

D.

monoclinc sulphur

E.

colloidal sulphur

Correct answer is C

rhombic Sulphur is prepared by allowing a saturated solution of Sulphur in carbon (iv) sulphide to evaporate slowly and crystals will gradually be deposited.

2,099.

Given that 1 mole of carbon -12 weighs 12.0g, how many atoms are there in 24.0g magnesium? (C = 12, Mg = 24, NA = 6.02 x 10 23mol-1)

A.

1/2 x 6.02 x 10 23

B.

1 x 6.02 x10 23

C.

2 x 6.02 x 10 23

D.

3x 6.02 x 10 23

E.

4x 6.02 x 10 23

Correct answer is B

No explanation has been provided for this answer.

2,100.

Which of the following is used extensively in manufacturing photographic chemicals?

A.

Aluminium chloride

B.

Zinc chloride

C.

Silver chloride

D.

Mercury (ll) chloride

E.

lron (ll) chloride

Correct answer is C

No explanation has been provided for this answer.