WAEC Chemistry Past Questions & Answers - Page 110

546.

A gaseous mixture contains 0,256 g of hydrogen and 2.00 g of oxygen. The mole ration of hydrogen to oxygen in the mixture is (H=1.00; O=16,0)

A.

1:1

B.

2:1

C.

1:4

D.

8:1

Correct answer is B

Mole = \(\frac{Mass}{Molar Mas}\) : \(\frac{Mass}{Molar Mass}\)
\(\frac{0.256}{2}\) : \(\frac{2}{32}
0. 128 : 0.0625
\(\frac{0.128}{0.0625}\) : \(\frac{0.0625}{0.0625}\)
2 : 1

547.

An aqueous solution of Na2CO3 is

A.

acidic

B.

alkaline

C.

amphoteric

D.

neutral

Correct answer is B

No explanation has been provided for this answer.

548.

How many lone pair (s) of electrons is present in HF?

A.

0

B.

1

C.

2

D.

3

Correct answer is D

No explanation has been provided for this answer.

549.

NH4- is formed from NH3 and H- by

A.

covalent bonding

B.

dative bonding

C.

hydrogen bonding

D.

ionic bonding

Correct answer is B

No explanation has been provided for this answer.

550.

The relative atomic mass of chlorine is not a whole number because

A.

it is the weighted average mass of all its various isotopes

B.

it is the average mass of all the isotopes of the element

C.

the element has strong oxidizing ability

D.

the atom contains a higher number of neutrons than protons

Correct answer is B

Chlorine is a mixture of two isotopes with different abundances. Its relative atomic mass is the mean or average of the isotopic masses.