Water acts as a universal solvent because:

1. It is an organic compound
2. It is polar and has a high dielectric constant.
3. It is liquid at room temperature.
4. It boils at 100°C

Permanent hardness of water is removed by:

1. Adding calcium sulphate
2. Boiling with potassium chloride
3. Boiling
4. Adding sodium carbonate

With a rise in temperature, the solubility of sodium chloride will:

1. Increase rapidly
2. Decrease
3. Remain the same
4. Increase slightly

The solubility of which of the following substances decreases with a rise in temperature :

1. Potassium chloride
2. Hydrated sodium sulphate
3. Calcium hydroxide
4. Potassium nitrate