Write a balanced equation for the reaction of – sulphur and hot concentrated nitric acid.

Dilute nitric acid is generally considered a typical acid except for its reaction with metals. In what way is dilute nitric acid different from other acids when it reacts with metals.

State why a yellow colour appears in conc. nitric acid when left standing in an ordinary glass bottle.

From the substances – Ammonium sulphate, Lead carbonate, Chlorine, Copper nitrate, Ferrous sulphate — State:

A compound which releases a reddish brown gas on reaction with conc. H₂SO₄ and copper turnings.