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.

3,801.

In the reaction between sodium hydroxide and sulphuric acid solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralise 10cm3 of 1.25 molar sulphuric acid?

A.

5cm3

B.

10cm3

C.

20cm3

D.

25cm3

E.

50cm3

Correct answer is E

\(2NaOH + H_{2}SO_{4} = Na_{2}SO_{4} + 2H_{2}O\)
V x 0.5M = 2(10 x 1.25)
0.5V = 2 x 12.5
0.5V = 25
V = \(\frac{25}{0.5}\) = \(50cm^{3}\)

3,802.

The periodic classification of elements is an arrangement of the elements in order of their

A.

Atomic Weights

B.

Isotopic Weights

C.

Molecular Weights

D.

Atomic Numbers

E.

Atomic Masses

Correct answer is D

Henry Moseley arranged the elements in the periodic table by their atomic number and this gave rise to the statement of the modern periodic law

3,803.

When sodium chloride and metallic sodium are each dissolved in water

A.

both processes are exothermic

B.

both processes are endothermic

C.

the dissolution of metallic sodium is endothermic

D.

the dissolution of metallic sodium is exothermic

E.

the dissolution of sodium chloride is explosive

Correct answer is D

When small quantities of sodium metal is added to water, there is an exothermic reaction, and they react to form sodium hydroxide and hydrogen.

3,804.

Zinc Oxide is a?

A.

Basic Oxide

B.

Acidic Oxide

C.

Amphoteric Oxide

D.

Neutral Oxide

E.

Reactive Oxide

Correct answer is C

Zinc oxide is an amphoteric oxide. 

- It will dissolve in both acids and alkalis

3,805.

Which of the following statements is NOT correct?

A.

The average kinetic energy of a gas is directly proportional to its temperature

B.

At constant tempearture, the volume of a gas increases as the pressure increases

C.

The pressure of a gas is inversely proportional to the density

D.

The temperature of a gas is directly proportional to its volume

Correct answer is B

Boyle's law is a gas law, stating that the pressure and volume of a gas have an inverse relationship. If volume increases, then pressure decreases.