Fill in the blanks:

(a) Water has ………………… density and …………….. volume at 4°C.

(b) Freezing mixture contains ……………… and ……………. .

(c) The solubility of a gas in water …………….. with rise in temperature and ………………….. with rise in pressure.

(d) ………………. is the purest form of natural water.

(e) Use of excessive ……………… by farmers causes water pollution.

(f) Boiling removes the ………………. hardness of water.

(g) Water turns the colour of anhydrous copper sulphate ………………. .

(h) The sticky substance formed when soap is added to hard water is …………………. .

Write true or false for the following statements and correct the false ones.

(a) Hard water forms lather easily with soap.

(b) Permanent hardness is due to bicarbonate salts of calcium and magnesium.

(c) Silica gel is a drying agent.

(d) The reaction of steam with magnesium produces hydrogen gas and magnesium hydroxide.

(e) An example of a colloid is ink.

Give one word/words for the following statements:

(a) Water fit for human consumption.

(b) The harmful substances dissolved in water.

(c) The change of states of water from one form to another.

(d) The gaseous form of water found in air.

(e) A mixture of common salt and ice.

(f) A substance which does not contain water in its chemical structure.

(g) A property due to which a substance absorbs water without dissolving.

(h) Water molecules in loose chemical combination with other substances.

Define:

(a) Soft water

(b) Hard water