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.

781.

The following diagram illustrates the rate curve that was obtained when Mg reacted with excess dilute HCl.

The diagram became horizontal at X because

A.

The reaction was slowed down

B.

All the dilute HCl has reacted

C.

All the Mg has reacted

D.

Hydrogen gas is produced at a steady rate

Correct answer is C

No explanation has been provided for this answer.

782.

Which of the following statements about intermolecular distances and cohesive forces between gas is correct? They are

A.

Both large

B.

Both negligible

C.

Constant and negligible

D.

Large and negligible

Correct answer is D

In a gas, the distance between molecules, whether monatomic or polyatomic, is very large compared with the size of the molecules; thus gases have a low density and are highly compressible.

Cohesive Force is negligible in case of gases.

783.

When a reaction is endothermic,

A.

Enthalpy change, \(\Delta\)H is negative

B.

Heat content of a product is less than the heat content of a reactant

C.

Heat content of reactants is less than the heat content of product

D.

The reaction is non-spontaneous

Correct answer is C

An endothermic reaction is any chemical reaction that absorbs heat from its environment. The absorbed energy provides the activation energy for the reaction to occur.

784.

Which of the following gases will diffuse most rapidly?

[H = 1.00, C = 12.0, O = 16.0, S = 32.0, Cl = 35.5]

A.

Cl2

B.

SO2

C.

CH4

D.

C2H6

Correct answer is C

No explanation has been provided for this answer.

785.

The vapour pressure of a liquid depends on:
I. Temperature II. rate of condensation III. Cohesive forces holding the particles together.

A.

I

B.

I and II

C.

I and III

D.

II and III

Correct answer is C

No explanation has been provided for this answer.