IGCSE Chemistry: Specimen Questions with Answers 94 - 96 of 240

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Question 94

Question

MCQ▾

14 moles of oxygen atoms contain ________ atoms. Given:

[Give your answer correct to two decimal places]

Choices

Choice (4)

a.

84.29

b.

84.27

c.

84.28

d.

84.26

Answer

c.

Explanation

Avogadro number is the number of atoms or molecules present in one mole of a substance.

The value of Avogadro number is

Therefore the number of atoms present in 1 mole of oxygen atoms is

Thus, the number of atoms present in moles of oxygen atoms

Question 95

Write in Short

Short Answer▾

Substances can be classified as:

Elements can be divided into:

Define each of the following terms:

compound

Explanation

a compound is a substance that results from a combination of two or more different chemical element s, in such a way that the atom s of the different elements are held together by chemical bonds that are difficult to break.

Question 96

Statement

True-False▾

In the following displacement reaction:

is a salt and is an acid. Can we obtain from the reaction between and ?

Choices

Choice (4)

a.

True

b.

False

c.

Both a. and b. are correct

d.

None of the above

Answer

c.

Explanation

No, we cannot obtain from the reaction between and .

Nitric acid, being a strong oxidising agent, cannot produce sulphuric acid, which is a reducing agent. Displacement reaction will not occur though the reaction seems to be displacement reaction.

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