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.

2,481.

When a piece of charcoal enclosed in a cylinder containing air is ignited

A.

the toatl volume of air is increased

B.

the relative amount of oxygen present is increased

C.

the relative amount of nitrogen present is decreased

D.

the relative amount of carbondioxide present is increased

E.

the ratio of oxygen to nitrogen in the system is increased

Correct answer is D

No explanation has been provided for this answer.

2,482.

The empirical formula of an oxide of nitrogen containing 30.4 per cent of nitrogen is (N=14.0,O=16.0)

A.

N2O2

B.

NO

C.

NO2

D.

N2O

E.

N2O3

Correct answer is C

No explanation has been provided for this answer.

2,483.

In the electrolysis of dilute sulphuric acid using platinum electrodes, the products obtained at the anode and cathode are:
Anode Cathode

A.

Sulphur hydrogen

B.

Hydrogen oxygen

C.

Oxygen Hydrogen

D.

Hydrogen sulphate ions

E.

Sulphur oxygen

Correct answer is C

Dissociation of sulfuric acid,

\(H_2SO_4→2H^+_{(aq)}+SO^{−2}_{4(aq)}\)

Dissociation of water,

\(H_2O→H^+_{(aq)} + OH^−_{(aq)}\)

At Anode : \(4OH^−→2H_2O_{(l)} + O_{2(g)} + 4e_{−}\)

At Cathode : \(2H^+_{(aq)}  + 2e^− → H_{2(g)}\)

2,484.

12 g of solid protassium chlorate (KCIO) were added to 40 g of water and heated to dissolve all the solid. As the solution cools, crystals of potassium chlorate at 66 oC. The solubility of potassium chlorate at 66 oC is therefore?

A.

66

B.

33

C.

10

D.

20

E.

30

Correct answer is E

solubility = \(\frac{solute x 100}{solvent}\)

The solubility of KClO3 at 66oC will be \(\frac{12}{40} \times \frac{100}{1}\)

= 30

2,485.

If chlorine gas is bubbled into water and then this yellowish-green coloured solution is exposed to bright sunlight for a while

A.

the solution will give out chlorine gas and hydrogen chloried gas

B.

the solution will produce chlorine gas and oxygen

C.

the solution will give out solution will producing hypochloric acid

D.

the solution is decomposed giving out oxygen, hydrogen and chlorine

E.

the solution will give out oxygen gas leaving behind aqueous hydrochloric acid

Correct answer is E

No explanation has been provided for this answer.