Name the sodium compound which is used for softening hard water.

What will happen if a solution of sodium hydrogen carbonate is heated? Give the equation of the reaction involved.

A solution turns red litmus blue, its pH is likely to be

1. 1
2. 4
3. 5
4. 10

A solution reacts with crushed egg-shells to give a gas that turns lime-water milky. The solution contains

1. NaCl
2. HCl
3. LiCl
4. KCl