Which one of the following is volatile in nature?

1. common salt
2. petrol
3. water
4. milk

An example of both physical and chemical change is:

1. burning of candle
2. melting of ice
3. cooking of food
4. glowing of bulb

When sugar is heated its colour changes into:

1. red
2. blue
3. black
4. grey

A pop sound is heard when a lighted match stick is brought near the mouth of a jar. This indicates the release of:

1. oxygen gas
2. hydrogen gas
3. nitrogen gas
4. water vapour