IGCSE Chemistry: Specimen Questions with Answers 138 - 140 of 240

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Question 138

Question

MCQ▾

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

Choices

Choice (4)

a.

Decomposition

b.

Direct Synthesis

c.

Double Displacement

d.

Single Displacement

Answer

c.

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 139

Question

MCQ▾

Group elements have … valence electron each.

Choices

Choice (4)

a.

2

b.

4

c.

3

d.

1

Answer

d.

Explanation

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

Question 140

Question

MCQ▾

Which property makes aluminum ideal for making food containers?

Choices

Choice (4)

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.

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