Explain with equation, what is noticed when permanent hard water is treated with

(a) slaked lime

(b) washing soda

What is permutit method, how can it be used for softening hard water ?

Explain:

(a) The use of lead pipes for drinking water supply is being discontinued.

(b) Chalk hills dissolve in rain water.

(c) Hard water is unfit for boilers.

(d) Iron chloride forms a saturated solution when exposed to the atmosphere.

(e) A bottle containing concentrated H₂SO₄ should be stoppered.

Some salts while crystallising out from their solutions, combine with a definite quantity of water. Some of these salts lose this water on exposure to dry air. Certain water soluble substances, when exposed to atmosphere at ordinary temperatures, absorb moisture from atmospheric air forming a saturated solution.

(a) State the term used for a 'definite quantity of water' combined with a salt.

(b) What type of salts lose their water molecules ? Give two examples.

(c) Table salt forms a solution on exposure to air during rainy season. Explain.

(d) How can pure sodium chloride be obtained from the above table salt solution in (c) ?