Question

justify how ice,water,and water vapour are three states of substances and not substances

Answer 1

Ice, water and water vapor are the three forms of water. When water is heated, it changes into it's gaseous state, vapor. When frozen, it turns into solid, ice. When condensed (in case it is still gas) it turns back into water, or when melted (if it is solid). Hence, they are three states of a substance, and not substances themselves. 

Answer 2

Ice , water and vapour are each solid , liquid and gasoues in state hence are states of substances but not substances