Hardness of water may be temporary or permanent. Permanent hardness is due to the presence of

a. Chlorides of Ca and Mg in water

b. Sulphates of Ca and Mg in water

c. Hydrogen carbonates of Ca and Mg in water

d. Carbonates of alkali metals in water.

Choose the correct option
1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)

Match the items in Column I with the relevant items in Column II.

Codes

Assertion: Permanent hardness of water is removed by treatment with washing soda.

Reason: Washing soda reacts with soluble magnesium and calcium sulphate to form insoluble carbonates.

1.  Both assertion and reason are true and the reason is the correct explanation of assertion.

2.  Both assertion and reason are true and the reason is not the correct explanation of assertion.

3.  Assertion is true but the reason is false.

4.  Assertion is false but the reason is true.

Which of the following ions will cause hardness in water sample?

1. Ca²⁺

2.  Na⁺

3.  Cl^-

4.  K⁺

A water softening reagent among the following is -

1. ${\mathrm{Ca}}_3{\left({\mathrm{PO}}_4\right)}_2$

2. ${\mathrm{Na}}_3{\mathrm{PO}}_4$

3. ${\mathrm{Na}}_6{\mathrm{P}}_6{\mathrm{O}}_{18}$

4. ${\mathrm{Na}}_2{\mathrm{HPO}}_4$