Question

How can we say that a matter is pure or impure?

Answer 1

Pure substances contains only one type of materials.an element such as gold is a pure substances because it is made up of atoms of which is identical. gas is a impure substance because it is a mixture of various constituents. 

Answer 2

Hi frnd,
we say that a matter is pure or impure

Pure substances

Elements and compounds are pure substances.

1. A pure substance has uniform composition and properties in all its parts, as it consists of particles of only one kind. For example, sugar and salt are pure substances.

Impure substances

Mixtures are impure substances.

1. A substance is said to be impure if it has particles of other substances mixed in it.