IGCSE Chemistry: Specimen Questions with Answers 70 - 73 of 240

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Question 70

Write in Short

Short Answer▾

Aluminum is used to make high voltage electricity cables.

Details of Four Metals

The table shows some properties of four metals which could be used for overhead power cables.

Overhead Power Cables

Suggest why steel, rather than copper, is used as a core for overhead power cables.

Explanation

Steel rather than copper is used as a core for overhead power cables because steel has less electrical conductivity than copper.

Question 71

Write in Short

Short Answer▾

The table shows some physical properties of the Group VII elements.

Some Physical Properties of the Group VII Elements

Use the information in the table to explain why

bromine is a liquid at room temperature …

Explanation

Bromine is a liquid because the intermolecular forces are strong enough so that it does not vapourise. Br forms diatomic molecules and van der Waals interactions are sufficiently strong.

Question 72

Question

MCQ▾

Choices

Choice (4)

a.

b.

c.

d.

Answer

c.

Explanation

HCl is an acid. Acids give ions when dissolved in water.

Question 73

Question

MCQ▾

The Relative Molecular Mass of water is________.

(Given that the Atomic Mass of hydrogen is . and the Atomic Mass of oxygen is .)

Choices

Choice (4)

a.

38

b.

18

c.

8

d.

28

Answer

b.

Explanation

2 atoms of hydrogen combine with 1 atom of oxygen to form 1 molecule of water.

=

= .

Thus the Relative Molecular Mass of water is

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