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.

1,046.

Which of the following laws is obeyed If at constant temperature, 200cm of hydrogen at 1.5 × 10m5Nm-2pressure becomes 300cm3 at 1.0 × 105Nm-2 pressure?

A.

Avogadro’s

B.

Boyle’s

C.

Charles’

D.

Faraday’s

E.

Graham’s

Correct answer is B

No explanation has been provided for this answer.

1,047.

The type of reaction ethyne mainly undergoes is

A.

addition

B.

carboxylation

C.

esterification

D.

saponification

E.

substitution

Correct answer is A

No explanation has been provided for this answer.

1,048.

What is the number of moles of NaHCO3in 250cm3 of its solution if the solution contains 8.4 g of NaHCO3 in 1 dm3 of the solution. [Na = 23, 0 = 16, C = 12, H = 1)

A.

1

B.

0.25

C.

0.05

D.

0.025

E.

0.01

Correct answer is D

no of mole in 250\(cm^3\) of its solution is about molar concentration.

using n = cv 

c = \(\frac{n}{v}\)

where c = molar concentration, n = number of moles and v = volume in \(dm^3\)

number of mole of NaHCO3 = mass of NaHCO3 / molar mass of NaHCO3 = \(\frac{8.4}{84}\) = 0.1moles

but v = 250\(cm^3\) = 250/1000 = 0.25\(dm^3\)

therefore c = 0.25 x 0.1 = 0.025mol\(dm^3\)

1,049.

In the reaction 2H2S(g) + SO2(g) → 2H2SO(I)+3S(s)SO2is acting as _agent

A.

a bleaching

B.

a dehydrating

C.

an oxidizing

D.

a precipitating

E.

a reducing

Correct answer is C

No explanation has been provided for this answer.

1,050.

What is the change in the oxidation number of phosphorus in the following reaction?

4P(s) + 5O2(ag) → 2P2O5(s)

A.

0 to 2

B.

0 to 5

C.

4 to 2

D.

4 to 5

E.

4 to 10

Correct answer is B

No explanation has been provided for this answer.