Question

2.
Which one of the following is not an example of a pure substance?
air
oxygen
carbon dioxide
copper​

Answer 1

Pure Substances are made of the same material throughout and having the same properties intact. They cannot be separated into other substances.

Pure substances can be elements or compounds. Examples of pure substances  are carbon dioxide, water and oxygen . pure substances can be elements or compounds.

Milk is a blend of water, carbohydrates, fats, proteins and many other .Thus it is a mixture.The milk extracted from cows is a mixture of water, fat and milk solids. The milk solids are made of proteins and carbohydrates.

Answer 2

Answer:

air

Explanation:

AIR IS NOT A PURE SUBSTANCE BECAUSE IT IS A HOMOGENEOUS MIXTURE OF DIFFERENT SUBSTANCES.