How many litres of water must be added to 1 litre of an aqueous solution of HCl with a pH of 1 to create an aqueous solution with pH of 2?

A solution of (–$$l$$) – chloro –1 – phenylethane in toluene racemises slowly in the presence of a small amount of SbCl₅, due to the formation of :

Which of the following exists as covalent crystals in the solid state?

The coagulating power of electrolytes having ions Na⁺, Al³⁺ and Ba²⁺ for arsenic sulphide sol increases in the order: