Chemistry

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 _.

A sample of n-octane (1.14 g) was completely burnt in excess of oxygen in a bomb calorimeter, whose heat capacity is 5 kJ K^-1 As a result of combustion reaction, the temperature of the calorimeter is increased by 5 K . The magnitude of the heat of combustion of octane at constant volume is ____ kJmol^-1 (nearest integer).