The major product of the following reaction is

Passing H₂S gas into a mixture of Mn²⁺, Ni²⁺, Cu²⁺ and Hg²⁺ ions in an acidified aqueous solution precipitates

Amongst the compounds given, the one that would from a brilliant coloured dye on treatment with NaNO₂ in dil. HCl followed by addition to an alkaline solution of $$\beta$$-naphthlol is

The following carbohydrate is