WAEC Chemistry Past Questions & Answers - Page 122

606.

An atom of an element X gains two electrons. The symbol of the ion formed is

A.

X +

B.

X 2+

C.

X 2-

D.

X -

Correct answer is C

X gained two electrons. X = 2-.

The ion formed is X\(^{2-}\).

607.

The formula of the compound formed between a trivalent metal, M and a divalent non-metal, Y is

A.

M2Y3

B.

M3Y2

C.

MY

D.

M3Y

Correct answer is A

M is a trivalent metal i.e M = 3+ ; Y is a divalent non-metal i.e Y = 2-

A reaction between M and Y will yield M\(_2\)Y\(_3\).

608.

The molecule which has a linear shape is

A.

CH4

B.

NH3

C.

H2S

D.

CO2

Correct answer is D

The shapes of the molecules are:

CH\(_4\) - Tetrahedral; NH\(_3\) - Trigonal pyramidal; H\(_2\)S - Bent; C)\(_2\) - Linear.

609.

Which of the following instruments is used in detecting the presence of radiation?

A.

Cathode ray tube

B.

Geiger-Muller counter

C.

Mass spectrometer

D.

X-ray tube

Correct answer is B

The Geiger- Muller counter is a device for measuring radioactivity by detecting and counting ionizing particles.

610.

Aluminium is extracted electrolysis from

A.

bauxite

B.

cryolite

C.

duralumin

D.

kaolin

Correct answer is A

No explanation has been provided for this answer.