CIE Chemistry (US-0439): Specimen Questions with Answers 138 - 140 of 240

Question number: 138

MCQ▾

Question

Suppose that you have and and you need to prepare . Which of the following methods would you use to prepare ?

Choices

Choice (4) Response

a.

Double Displacement

b.

Single Displacement

c.

Decomposition

d.

Direct Synthesis

Answer

a.

Explanation

Here we have and and we need to prepare

If we mix and the reaction that would take place:

This is the method of Double Displacement and we can observe that is produced.

Thus to prepare we use the method of double displacement.

Question number: 139

MCQ▾

Question

Group elements have ________ valence electron each.

Choices

Choice (4) Response

a.

2

b.

1

c.

3

d.

4

Answer

b.

Explanation

Group 1A elements have one valence electron each. Examples of group 1A elements include lithium, sodium, potassium etc.

Question number: 140

MCQ▾

Question

Which property makes aluminum ideal for making food containers?

Choices

Choice (4) Response

a.

Conducts electricity

b.

Conducts heat

c.

Mechanical strength

d.

Resistance to corrosion

Answer

d.

Explanation

Correct option is D i. e. because Aluminium corrosion resistance is very good in untreated aluminium. Untreated Aluminium has very good corrosion resistance in most environments. This is primarily because Aluminium spontaneously forms a thin but effective oxide layer that prevents further oxidation.