A blue crystalline solid 'X' on heating gave a reddish brown gas 'Y', a gas which relits a glowing splint and a residue which is black. Identify X and Y, and write the equation for the action of heat on X.

Choose from the list of substances – Acetylene gas, aqua fortis, coke, brass, barium chloride, bronze, platinum. A catalyst used in the manufacture of nitric acid by Ostwald's process.

Choose the correct answer from the choices given – The brown ring test is used for detection of:

(A) CO₃^2-
(B) NO₃^1–
(C) SO₃^2-
(D) C1^1-

(i) State the special feature of the apparatus used in the laboratory preparation of nitric acid?

(ii) State why the temperature of the reaction mixture of HNO₃ is not allowed to rise above 200°C.