Classify each of the following, as a physical or a chemical change. Give reasons.
1. Drying of a shirt in the sun.
2. Rising of hot air over a radiator.
3. Burning of kerosene in a lantern.
4. hange in the colour of black tea on adding lemon juice to it.
5. Churning of milk cream to get butter.
1. It is a physical change. Moisture or water drops present on the shirt will evaporate or change into vapours.
2. It is a physical change. On cooling, the level of air over the radiator will fall.
3. It is a chemical change. The hydrocarbons present in kerosene will react chemically with oxygen to form new products.
4. It is a chemical change. The acid present in lemon juice will react with the constituents (e.g. caffeine) present in black tea.
5. It is a physical change. However, butter will not change to milk so easily.