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.

2,841.

Soap lather is an example of a colloid in which a?

A.

liquid is dispersed in gas

B.

solid is dispersed in liquid

C.

gas is dispersed in liquid

D.

liquid is despersed in liquid

Correct answer is C

No explanation has been provided for this answer.

2,842.

90.0g of MgCI2 was placed in 50.0cm3 of water to give a saturated solubility of the salt is 8.0 mol dm3 at the same temperature, what is the mass of the salt left undissolved at the given temperature?

(Mg = 24, Cl = 35.5)

A.

52.0g

B.

58.5g

C.

85.5g

D.

88.5g

Correct answer is A

Molar mass of MgCl2 = 95g
The solubility of MgCl2 is 8.0/dm3
1 dm3 = 1000cm3
Solubility of g/cm3
8 x 95 → 1000cm3
x → 50
x = (50)/(1000) x (8 x 95) / (1) = 38g
Mass of the salt left undissolved = 90 - 38 = 52.0g

2,843.

If an element X of an atomic number Z and mass number Y is irradiated by an intense concentration of neutrons, the relevant nuclear equation is?

A.

yzX + 10n → y - 1z + 1X

B.

yzX + 10n → y + 1zX

C.

yzX + 10n → yz + 1X

D.

yzX + 10n → y + 1z - 1X

Correct answer is B

No explanation has been provided for this answer.

2,844.

Excess phosphorus was burnt in a gas jar and the residual gas passed successively over concentrated KOH solution and concentration H2SO4 before being collected in a flask. The gases collected are?

A.

carbon (IV) oxide, nitrogen and the rare gases

B.

nitrogen and the rare gases

C.

carbon (IV) oxide, nitrogen (IV) oxide and the rare gases

D.

carbon (IV) oxide

Correct answer is B

So phosphorus will remove oxygen by forming P205, KOH will absorb water vapors, and sulfuric acid will react with carbon dioxide thus removing it from the mixture. So nitrogen and rare gases will be left

2,845.

The soil around a battery manufacturing factory is likely to contain a high concentration of?

A.

Ca2+ salts

B.

Pb2+ salts

C.

Mg2+ salts

D.

Al3+ salts

Correct answer is B

No explanation has been provided for this answer.