Convert (i) NaHCO₃ (ii) Na₂CO₃ to unstable carbonic acid by action with dil. H₂SO₄.
State the reason why ammonia is evolved when an ammonium salt and alkali are heated.

Define pH value. What would you say about the pH of a solution in which

(i) H⁺ aq. ions = OH^- ions

(ii) evolves CO₂ when heated with Na₂CO₃

(iii) OH^-ions > H⁺ aq. ions.

State the colour change in a neutral litmus in presence of (i) acidic (ii) alkaline medium.

State the colour change in a universal indicator e.g. pH paper on

(i) slightly acidic soil

(ii) slightly alkaline soil

(iii) dairy milk

(iv) human blood tested for medical diagnosis.