WAEC Chemistry Past Questions & Answers - Page 128

636.

The number of atoms in one mole of a substance is equal to the

A.

mass number

B.

oxidation number

C.

atomic number

D.

avogadro number

Correct answer is D

No explanation has been provided for this answer.

637.

What is the amount of magnesium that would contain 1.20 x 1024 particles? [Mg = 24, Avogadro's constant = 6.02 x 1023]

A.

0.5 moles

B.

2.0 moles

C.

12.0 moles

D.

24.0 moles

Correct answer is B

No explanation has been provided for this answer.

638.

Consider the reaction represented by the following equation: xKMnO 4(aq) + ySO2(g) + zH2O(I) → K 2SO4(AQ) + 2MnSO4(aq) + 2H2SO x,y and z are respectively

A.

2,5 and 2

B.

2,2 and 5

C.

5, 1 and 2

D.

1, 5 and 2

Correct answer is A

No explanation has been provided for this answer.

639.

The volume occupied by 17g of H2S at s.t.p. is [H = 1.00, S = 32.0, Molar volume = 22.4 dm3]

A.

11.2dm 3

B.

17.0 dm3

C.

34.0dm 3

D.

44.8dm 3

Correct answer is A

No explanation has been provided for this answer.

640.

Which of the following statements about displacement reaction is correct?

A.

A more electropositive element displaces a less electroposive one

B.

A less electropositive element displaces a more electropositive one

C.

The position of elements in the reactivity series has no effect on the reaction

D.

it only occurs when the reaction is at equilibrium

Correct answer is A

No explanation has been provided for this answer.