Physical changes:

The substance involved in a physical change is structurally identical before and after the change. Texture, shape, temperature, and a change in the state of matter are examples of physical changes.

Magnetization of iron is a physical change as it is a temporary change.

For chemical change, new substances are formed and the process is mostly irreversible.

Only crumpling of paper is physical change since no substance is formed. Crumpled paper is still paper.

Physical changes:

The substance involved in a physical change is structurally identical before and after the change. Texture, shape, temperature, and a change in the state of matter are examples of physical changes.

Magnetization of iron is a physical change as it is a temporary change.

Physical change is reversible and no new substance is formed.

All the options except melting of ice are chemical change because new substances are formed and the process is also not reversible.

For the melting of ice, it can be frozen into ice again so it is reversible and the substance is still water in different forms.

For a physical change, no new substance(s) are formed and the change is reversible. The sugar can be separated from the water by means of distillation and therefore reversible.

For a physical change, no new substance is formed. All the options except the "solidification of water into ice" are chemical changes since new substances are formed. Rusting of iron form oxidized iron, burning of wood forms ashes, chemical reaction of hydrogen and oxygen forms water.

In chemical change too, the process is not reversible but a physical change is reversible. For the solidification of water into ice, the ice could be melt back to water.

On addition of saliva which contains an amylase to the cooked yam, a starch digesting enzyme (chemical compound that catalyzes the breakdown of starch), the starch gradually converts to sugar (new substance formed).

I and II are chemical changes. For chemical change, new substances are formed and the process is not reversible.

Physical and chemical changes are similar because matter experiences a change in state, Physical changes are different because matter remains the same substance, just in a different state, whereas chemical changes change the matter. A chemical change results from a chemical reaction, while a physical change is when matter changes forms but not chemical identity. Examples of chemical changes are burning, cooking, rusting, and rotting. Examples of physical changes are boiling, melting, freezing, and shredding.