State how —

(i) a higher ratio of the reactant air

(ii) exothermicity of the catalytic reaction

(iii) use of low temp. in the conversion of NO to NO₂ — affects each related step in Ostwald's process.

State why nitric acid

(i) stains the skin

(ii) cannot be concentrated beyond 68% by boiling.

State the change in colour of pure concentrated nitric acid on initial and prolonged decomposition.

State the cation responsible for turning moist neutral litmus red on reaction with dil. HNO₃.