Explain:

Chemical change

Mark True or False beside each sentence.

When heated, $\mathrm{ZnO}$ undergoes a physical change.

Mark True or False beside each sentence.

A chemical change is easily reversed.

Mark True or False beside each sentence.

Energy is either evolved or absorbed in a chemical change.

Mark True or False beside each sentence.

When heated iodine undergoes a physical change.

Mark True or False beside each sentence.

When an element undergoes a chemical change, its weight changes.

State whether the following is a physical or chemical change. Explain by giving reason.

Burning of charcoal

State whether the following are physical or chemical changes. Explain by giving a reason.

Rusting of iron.