a. A small amount of acid or alkali is added before electrolysis of water. Why?
b. What happens when:
i. Hydrolith is treated with water.
ii. Heavy water reacts with aluminium carbide.

Explanation

a Pure water being a weak electrolyte and feebly ionised is a bad conductor of electricity. In order to make it good conductor, a small amound of acid or alkali is added before electrolysis
(b) (i) Hydrolith, i.e., `CaH_(2)` on hydrolysis gives calcium hydroxide, `Ca(OH)_(2)` with the evolution of dihydrogen gas `H_(2)`.
`CaH_(2)+2H_(2)OtoCa(OH)_(2)+2H_(2)uarr`
(ii) Deuteromethane is evolved when heavy water reacts with aluminium carbide.
`underset("carbide")underset("Aluminium")(Al_(4)C_(3))+underset("water")underset("Heavy")(D_(2)O)to4Al(OH)_(3) darr +underset("Deuteromethane")(3CD_(4))`