The aqueous solution of a salt (A) is alkaline. When (A) is heated strongly, it swells up and melts to give a transparent bead. When the bead is heated with a sulphate salt (C), the bead becomes deep blue in colour. A white crystalline compound (D) is obtained when concentrated `H_2SO_4` is added to a hot solution of (A). Identify (A), (B), (C) and (D) and give the reactions involved.

An organic compound A (C_8H_6) reacts with dilute H_2SO_4 in presence of mercuric chloride to produce another compound (B) . B is also obtained when benzene reacts with an acid chloride in presence of anhyd. AlCl_3 . Identify A and B and give the reactions involved.

A liquid A is treated with Na_(2)CO_(3) solution. A mixture of two salts B and C are produced in the solution. The mixture on acidification with H_(2)SO_(4) and distillation produces the liquid A again. Identify A, B and C and write the equations involved.

When dilute HCI is added to a white substance (A), a colourless gas (B) is evolved. When the gas (B) is passed through clear lime water, a white precipitate ( C) is obtained. The precipitate dissolves when excess of the gas (B) is passed through the lime water. The residue obtained on heating the solid substance (A) is yellow when hot but white when cold. When the gas (B) is passed through red hot charcoal, another gas (D) is obtained. The gas (D) gets absorbed in arnmoniacal cuprous chloride solution . Identify (A), (B), (C) and (D) and give the relevant reactions.

An aqueous solution of a gas (X) -turns red litmus blue. When excess of this solution is added to copper sulphate solution, it turns deep blue. When this solution is added to FeCl_(3) solution, a brownish precipitate soluble in HNO_(3) is obtained. Identify the gas (X) and write balanced equations for each of the reaction involved.

A white solid (A) when heated liberates a colourless gas which does not support combustion. The residue is dissolved in water to form (B) which can be used for whitewashing. When excess of CO_2 gas is passed through the solution of (B), it gives a compound {C) which on heating forms (A). Identify (A), (B) and (C). Give the reactions.

An aqueous solution of a gas 'A ' gives the following reactions along with same observations: When H_(2)S is passed through the solution, it becomes turbid. Identify the gas 'A' , and give equation of the reaction involved in each case.

A certain salt X, gives the following result. When conc. H_2SO_4 is added to a hot solution of X, white crystal of a acid Z separates out. Write equation for all the above reactions and identify X, Y and Z.

A green oxide of chromium(A), on fusion with KOH and KNO_3 gives a yellow compound (B). The aqueous solution of (B) on acidification with dilute H_2SO_4 gives an orange coloured compoud (C). Identify (B) and (C) and write down balanced chemical equations involved.