A. Add a teaspoon of salt to half a beaker of water.
Transfer the mixture into a dish and let the water evaporate.

B. Similarly, make a mixture of alum and water.
Let the water evaporate.

What remains in dishes 'A' and 'B' when the water evaporates completely?

A. Add a teaspoon of salt to half a beaker of water.
Transfer the mixture into a dish and let the water evaporate.

B. Similarly, make a mixture of alum and water.
Let the water evaporate.

Were you able to recover all the salt from A and B that was dissolved in the water?

Classify the following as pure substances and mixtures.
• air • milk • water vapour • baking soda • tap water • soil • pineapple juice • gold • seawater • lemonade • sugar • iron • alum crystal • oxygen • silver • petroleum.