1What kind of change is called a physical change? Write it with examples.
2What is a chemical change? Give three practical examples related to our daily life.
3Write the difference between a physical change and a chemical change.
4Classify these as physical or chemical change: evaporation of water, boiling an egg, condensation of steam, burning of mineral fuel, sugar dissolving in water.
5Give the reason: the process in which a lump of salt breaks into powdered salt is a physical change.
6Give the reason: the process in which hydrogen and oxygen combine to make water is a chemical change.
7Why are aluminium frames usually not painted, while iron frames must be painted again and again?
8Burning a heavy log leaves only a small heap of ash. Was matter destroyed? Explain.
9Milk becoming curd and salt dissolving in water both look final. Why is one chemical and the other physical?
10Explain, in terms of molecules, why a physical change can be reversed and a chemical change cannot.