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

14 moles of oxygen atoms contain ________ atoms. Given:

[Give your answer correct to two decimal places]

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

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.

In the following displacement reaction:

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

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.