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

Given below are two statements: 

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