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.

3,736.

Which of the following statement is true of the electrochemical series?

A.

Electropositivity of metals increase down the series

B.

Electropositivity of non-metals decrease down the series

C.

Electronegativity of non-metals decrease down the series

D.

Electropositivity of metals decreases down the series

Correct answer is D

No explanation has been provided for this answer.

3,737.

RS(aq) + HF(aq) → RF(s) + HS(aq)
ΔH = -65.7 kj mol(-1).
From the equation above, it can be deduced that

A.

the heat content of the reactants is lower than that of the products

B.

the heat content of the reactants is higher than that of the products

C.

the reaction is slow

D.

a large amount of heat is absorbed

Correct answer is B

No explanation has been provided for this answer.

3,738.

When a current I was passed through an electrolyte solution for 40 minutes, a mass X g of a univalent metal was deposited at the cathode. What mass of the metal will be deposited when a current 2I is passed through the solution for 10 minutes?

A.

X/4 g

B.

X/2 g

C.

2X g

D.

4X g

Correct answer is B

From M = zit
Where M = to the mass of the metal liberated
z = Is the electrochemical equivalent
∴ X g = 1 * 1 * 40 * 60
X g = 2400 I
Let Y represent the new mass
Y = 1*2I * 10 * 60
Y = 1200 I
Y/(X g) = 1200 I/2400 I
Y = X/2 g

3,740.

What quantity of electricity will liberate 0.125 mole of oxygen molecules during the electrolysis of dilute sodium chloride solution?
[ F = 96 5000 C mol-1 ]

A.

24 125 coulombs

B.

48 250 coulombs

C.

72 375 coulombs

D.

96 500 coulombs

Correct answer is B

4 Faradays of electricity is required to liberate one mole of oxygen gas
∴ quantity of electricity required
= 0.125 * 4 * 96500 = 48250 coulombs