John wanted to know about the composition of air. He asked Sam to explain it to him whether air is composed of a single component or more than one component. To reply this query Sam made the following statements:
Statement I: Air is a mixture of gases, water vapour and dust particles.
Statement II: Air is composed of only one gas that is nitrogen.
Statement III: Air is composed of two gases, nitrogen and oxygen only.
Statement IV: Air is made up of more than one components.
Which of the above statement(s) are correct?