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.

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.

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.