WAEC Chemistry Past Questions & Answers - Page 31

151.

Which of the following oxides has a giant covalent structure?

A.

Al\(_2\)O\(_3\)

B.

Na\(_2\)O

C.

P\(_4\)O\(_10\)

D.

SiO\(_2\)

Correct answer is D

- Silicon dioxide is an example of a substance with a giant covalent structure . It contains many silicon and oxygen atoms. All the atoms in its structure are linked to each other by strong covalent bonds. The atoms are joined to each other in a regular arrangement, forming a giant covalent structure.

152.

The bond between NH\(_3\) and H\(^+\) in NH4\(^+\) is?

A.

dative

B.

covalent

C.

hydrogen

D.

electrovalent

Correct answer is A

No explanation has been provided for this answer.

154.

What volume of oxygen at s.t.p is required to burn completely 7.5 dm\(^3\) of methane according to the following equation?

CH\(_4\) \(_g\) + 20\(_2\) \(_g\)  → CO\(_2\) \(_g\) + H\(_2\)O\(_g\)

A.

3.75 dm\(^3\)

B.

7.59 dm\(^3\)

C.

15.0 dm\(^3\)

D.

30.0dm\(^3\)

Correct answer is C

1 mole of methane reacts with 2 moles of oxygen

1 vol of methane reacts with 2 vol of oxygen

: 7.5  vol of methane will yield 15 vol of oxygen in dm\(^3\)

155.

The initial volume and pressure of a given mass of gas is V and 3.P. What is its pressure if its volume is increased to  2V at constant temperature?

A.

3P

B.

2P

C.

\(frac{3}{2}\) P

D.

\(frac{2}{3}\) P

Correct answer is C

No explanation has been provided for this answer.