Question

Which of the following is a physical change ?

• A. solubility in water
• B. combustibility
• C. oxidation
• D. reaction with water

Answer 1

The correct option is A solubility in water

1. A physical change is reversible, a chemical change is not. For example, the freezing of water would be a physical change because it can be reversed, whereas the burning of wood is a chemical change, you can't 'unburn' it.

2. A physical change is a change in which no new substance is formed; a chemical change results in the formation of one or more new substances. Again, consider the previous examples: Freezing water into ice just results in water molecules which are 'stuck' together, it's still $H_{2}O$. Whereas burning wood results in ash, carbon dioxide etc.

So, solubility just changes phase and it is a physical change.