State the colour of :

(i) pure nitric acid

(ii) nitric acid obtained in the laboratory

(iii) nitric acid obtained in the laboratory after passage of air or addition of water to it.

State which reaction of ammonia forms the first step of Ostwald's process.

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.