Classify each of the following as a physical or a chemical change. Give reasons.
- Drying of a shirt in the sun.
- Rising of hot air over a radiator.
- Burning of kerosene in a lantern.
- Change in the colour of black tea on adding lemon juice to it.
- Churning of milk cream to get butter.
Answer:
- It is a physical change because water is converted from its liquid state to gaseous state because of the sun’s heat.
- It is a physical change because water in the radiator is converted from a liquid state to gaseous state.
- It is a chemical change because combustion of kerosene occurs and new products are formed.
- It is a chemical change because there is a reaction between the citric acid in the lemon and the compounds of tea resulting in formation of new products.
- It is a physical change because the cream suspended in the milk is separated by churning.