Which of the following is a physical change? Digesting foodBoiling waterRusting of ironBurning wood

The physical change among the options given is "Boiling water".

Here's why:

1. Digesting food: This is a chemical change because it involves breaking down food substances into simpler forms through chemical reactions.

2. Boiling water: This is a physical change. When water boils, it changes from a liquid to a gas (steam), but it is still water. No new substances are formed.

3. Rusting of iron: This is a chemical change. Rusting involves iron reacting with oxygen to form a new substance, which is rust (iron oxide).

4. Burning wood: This is also a chemical change. When wood burns, it reacts with oxygen in the air to form new substances like ash, smoke, and gases.

So, the only physical change in the list is boiling water.