WAEC Chemistry Past Questions & Answers - Page 256

1,276.

The number of atoms in 1.2g of carbon - 12 isotope is

A.

1.00 x 10 22

B.

6.02 x 1022

C.

1.20 x 10 23

D.

1.00 x 1023

E.

6.02 x 1024

Correct answer is B

No explanation has been provided for this answer.

1,277.

The oxidation number of phosphorus in PO 3/4 is

A.

+1

B.

+2

C.

+3

D.

+4

E.

+5

Correct answer is E

No explanation has been provided for this answer.

1,278.

Which of the following would increase the rate of reaction of chips of a metal M as shown in the equation below? M(s) + 2HCI(aq) → MCI2(aq) + H2(g)

A.

Diluting the hydrochloric acid

B.

Adding some distilled water

C.

Decreasing the temperature

D.

Grinding the metal into powder

E.

Increasing the pressure

Correct answer is D

No explanation has been provided for this answer.

1,279.

Which of the following is not a property of magnesium oxide?

A.

High melting point

B.

Dissolution in polar solvents

C.

Presence of ionic bonds

D.

Possession of crystal lattice

E.

Low binding energy

Correct answer is E

No explanation has been provided for this answer.

1,280.

In any chemical reaction, the total mass of the products is always equal to that of the reactants. This is statement of the law of

A.

definite proportion

B.

conservation of matter

C.

reciprocal proportions

D.

constant composition

Correct answer is B

No explanation has been provided for this answer.