CIE Chemistry (US-0439): Specimen Questions with Answers 39 - 41 of 240

Question number: 39

MCQ▾

Question

The general formula of alkane is:

[n is the number of carbon atoms present in the organic compound]

Choices

Choice (4) Response

a.

b.

c.

d.

Answer

a.

Explanation

The general formula of alkane is where n is the number of carbon atoms.

For

For .

For

Question number: 40

MCQ▾

Question

Number of valence electrons of the elements present in group is/are ________.

Choices

Choice (4) Response

a.

1

b.

2

c.

3

d.

5

Answer

a.

Explanation

Correct option is A. Number of valence electrons of the elements present in group is .

In fact the group number denotes the number of valence electrons present in the atoms of the elements present.

Its electronic configuration is .

electronic configuration is 2,8,1

Electronic Configuration is 2,8, 1

electronic configuration is 2,8, 1

Question number: 41

MCQ▾

Question

Pure metals conduct electricity and can be hammered into different shapes.

Why are metals sometimes used as alloys?

Choices

Choice (4) Response

a.

Alloys are cheaper than the metals they are made from.

b.

Alloys are easier to hammer into different shapes.

c.

Alloys are harder and keep their shape better.

d.

Alloys conduct electricity better.

Answer

a.

Explanation

Correct option is A i. e. Alloys are cheaper than the metals they are made from because An alloy is a mixture of two elements, one of which is a metal. Alloys often have properties that are different to the metals they contain. This makes them more useful than the pure metals alone. For example, alloys are often harder than the metal they contain.