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.

3,641.

The main impurity in iron ore during the extraction of iron is

A.

Silicon (IV) oxide

B.

Carbon (IV) oxide

C.

Calcium trioxosilicate

D.

Sulphur (II) oxide

Correct answer is A

No explanation has been provided for this answer.

3,642.

The general formula for the alkanals is

A.

ROH

B.

R2CO

C.

RCOOR1

D.

RCHO

Correct answer is D

No explanation has been provided for this answer.

3,643.

Fermentation is the

A.

breaking down of carbohydrate to glucose

B.

conversion of sugar to alcohol in the presence of yeast

C.

breaking down of sugar to carbohydrate

D.

conversion of alcohol to sugar in the presence of yeast

Correct answer is B

No explanation has been provided for this answer.

3,644.

NH3(g) + HCl(g) → NH4Cl(s)
The entropy change in the system above is

A.

negative

B.

indeterminate

C.

positive

D.

zero

Correct answer is A

The entropy change for the transition from gas to solid is negative because solids have lower entropy compared to gases, gas particles are more disordered and have a higher rate of motion compared to solids that have closely packed particles

3,645.

In which of the following reactions has the oxidation number of nitrogen increased?

A.

2NO(g) + Br2(l) → 2NOBr(l)

B.

2NO(g) + O2(g) → 2NO2(g)

C.

FeSO4(aq) + NO(g) → Fe(NO)SO4(s)

D.

2NO(g) + Cl2(g) → 2NOCl(l)

Correct answer is B

No explanation has been provided for this answer.