IGCSE Chemistry: Specimen Questions with Answers 218 - 221 of 240

Question number: 218

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MCQ▾

Question

After the stone age, the first metal to be used by early man to make tools was ________.

Choices

Choice (4) Response

a.

Silver

b.

Iron

c.

Copper

d.

Golden

Answer

c.

Explanation

After the stone age, the first metal to be used by early man to make tools was copper.

Question number: 219

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Short Answer Question▾

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Substances can be classified as:

Elements can be divided into:

copper

Explanation

Copper is a chemical element with symbol Cu (from Latin: cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a reddish-orange color.

Question number: 220

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Question

For purification of common salt we use ________ acid.

Choices

Choice (4) Response

a.

Nitric acid

b.

Sulphuric acid

c.

Hydrochloric acid

d.

Vinegar

Answer

c.

Explanation

For purification of common salt we use hydrochloric acid.

Question number: 221

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Question

The equation shows the formation of from .

Statements refer to this reaction.

1. sulfate is reduced to sulfate.

2. The (II) in the name refers to the oxidation state of the metal.

3. The reaction is reversible.

Which statements are correct?

Choices

Choice (4) Response

a.

b.

c.

d.

Answer

d.

Explanation

Correct option is D i. e. only (The reaction is reversible) because water driven is off from anhydrous Copper sulfate and endothermic energy is done and when it heated it form again forms anhydrous copper sulfate. So the reaction is reversible.