Chemistry

[P] on treatment with Br2/FeBr3 in CCl4 produced a single isomer C8H7O2Br while heating [P] with sodalime gave toluene. The compound [P] is:

On heating, lead (II) nitrate gives a brown gas (A). The gas (A) on cooling changes to a colourless solid/liquid (B). (B) on heating with NO changes to a blue solid (C). The oxidation number of nitrogen in solid (C) is:

The pair in which both the species have the same magnetic moment (spin only) is:

The region in the electromagnetic spectrum where the Balmer series lines appear is:

The decreasing order of reactivity of the following organic molecules towards AgNO3 solution is:
(A) Cl
(B) Cl OMe
(C) CH3CHCH3 Cl
(D) CH3CHCH2NO2 Cl

Among statements (a) - (d), the correct ones are:

(a) Lime stone is decomposed to  during the extraction of iron from its oxides.

(b) In the extraction of silver, silver is extracted as an anionic complex.

(c) Nickel is purified by Mond's process.

(d) Zr and Ti are purified by Van Arkel method.

The total number of structural isomers possible for the substituted benzene derivatives with the molecular formula C?H? is _.