A dilute acid B does not normally give hydrogen when reacted with metals but does give a gas when reacts with copper. Identify B. Write equation with copper.

State one observation :

(a) Concentrated nitric acid is reacted with sulphur.

(b) Lead nitrate is heated strongly in a test tube.

(c) Zinc nitrate crystals are strongly heated.

(d) when crystals of copper nitrate are heated in a test tube.

Give balanced equation for the following :

(a) dilute nitric acid and copper carbonate.

(b) oxidation of carbon with conc. HNO₃.

(c) Laboratory preparation of nitric acid.

(d) Action of heat on a mixture of copper and concentrated nitric acid.

X, Y and Z are three crystalline solids which are soluble in water and have a common anion.
To help you to identify X, Y and Z, you are provided with the following experimental observations. Copy and complete the corresponding inferences in (a) to (e).

(a) A reddish-brown gas is obtained when X, Y and Z are separately warmed with concentrated sulphuric acid and copper turning added to the mixture.

INFERENCE 1: The common anion is the …………… ion.

(b) When X is heated, it melts and gives off only one gas which re-lights a glowing splint.

INFERENCE 2: The cation in X is either …………… or ……………

(c) The action of heat on Y produces a reddish-brown gas and a yellow residue which fuses with the glass of the test tube.

INFERENCE 3: The metal ion present in Y is the …………… ion.

(d) When Z is heated, it leaves no residue. Warming Z with sodium hydroxide solution liberates a gas which turns moist red litmus paper blue.

INFERENCE 4: Z contains the …………… cation.

(e) Write the equations for the following reactions.

1. X and concentrated sulphuric acid (below 200° C). (One equation only for either of the cations given in INFERENCE 2).
2. Action of heat on Y.
3. Concentrated nitric acid is added to copper turnings kept in a beaker.