Question

Is air a pure substance?

Answer 1

Hint: A compound is formed due to its different types of bonds formed between the constituents of it. All the compounds are different due to the nature of bonds which are present between the atoms of elements. A compound is a pure substance.

Complete answer: - A pure substance is a substance which has only one type of atom or molecule thereby having a constant composition and structure.
- A compound is a pure form of substance which contains the atoms of the constituent elements. They are formed when elements are joined and held together by strong forces called chemical bonds.
- Elements and compounds are pure substances. Elements are substances composed of only one type of atom. For example, copper, silver, oxygen etc.
- The compounds or mixtures are substances formed by the addition of two or more different elements. For example water is a compound and it is going to be formed by the combination of two moles of hydrogen and one mole of oxygen.
- Air is not supposed to be considered as a pure substance. Because air is a mixture of different gases.
- Air mostly contains nitrogen and oxygen in about 78% and 20% respectively.

Note: Elements and compounds have a constant composition throughout and can thus be said as pure substances. While a mixture has different characteristics than a pure substance. They are known as impure substances. Mixtures are composed of different compounds mixed together, or more than one pure substance combined together in any proportion.