Question

how do we concluded that freezing and melting of ice and water is physical change

Answer 1

since the melting of Ice and freezing of water are reversible changes we conclude that they are physical change

Answer 2

Dear friend,
Here's your answer...
Physical change is the type of change in which only shape, size, state and composition of a substance changes. It is reversible.
In freezing of water to form ice and melting of ice, the state , shape and size of water is changed from solid to liquid or from liquid to solid. Freezing and melting of ice is reversible change.
#Hope it helps you!!