Question

since sulphar(non metal) is very reactive metal.Then why it does not react with air,when taken in deflagerating spoon for heating purpose?

Answer 1

Sulphur does not react with air at room temperature. Thus, when it is taken in deflagrating spoon, it is heated to a certain temperature. Then it starts burning which results in formation of sulphur dioxide.
S + O₂ → SO₂