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.

546.

Which of the following gases is not acidic?

A.

\(SO_{3}\)

B.

\(NO_{2}\)

C.

\(Co_{2}\)

D.

CO

Correct answer is D

The compound CO is treated as a neutral oxide, though in truth, it is slightly acidic. Regardless of this, within the options supplied, CO is the best option available.

547.

When Magnesium reacts with oxygen, heat is 

A.

absorbed and the reaction is endothermic

B.

evolved and the reaction is endothermic

C.

evolved and the reaction is exothermic

D.

absorbed and the reaction is exothermic

Correct answer is C

The Magnesium actually reacts with oxygen in the air, is burnt and produces a bright light. The bright light emits a lot of heat so the reaction is exothermic.

548.

The number of atoms present in 2.5moles of a triatomic gas is equivalent to   [1mole = \(6.02\times 10^{23}\)]

A.

\(2.5\times 10^{23}\)

B.

\(1.5\times 10^{23}\)

C.

\(1.5\times 10^{24}\)

D.

\(2.5\times 10^{24}\)

Correct answer is C

1 mole = \(6.02 \times 10^{23}\)

2.5 moles = \(6.02 \times 10^{23} \times 2.5\)

= \(15.05 \times 10^{23} = 1.505 \times 10^{24}\)

\(\approxeq 1.5 \times 10^{24}\)

549.

In a saturated solution at a given temperature, the undissolved solutes are in equilibrium with

A.

the solvent

B.

dissolved solute particles

C.

the saturated solution

D.

insoluble solute particles

Correct answer is C

A solution that is in equilibrium with undissolved solute is said to be saturated.

550.

Graphite and Diamond are similar in that they

A.

have octahedral shape

B.

have same density

C.

form carbon(IV) oxide on combustion

D.

conduct electricity

Correct answer is C

A diamond is pure carbon. Graphite is pure carbon. Both will burn to form carbon dioxide.