The unit of the van der Waals gas equation parameter 'a' in $$\left( {P + {{a{n^2}} \over {{V^2}}}} \right)(V - nb) = nRT$$ is :

In polythionic acid, H₂S_xO₆ (x = 3 to 5) the oxidation state(s) of sulphur is/are :

Tyndall effect is more effectively shown by :

In Carius method for estimation of halogens, 0.2 g of an organic compound gave 0.188 g of AgBr. The percentage of bromine in the compound is ______________. (Nearest integer)

[Atomic mass : Ag = 108, Br = 80]