Identify the cation (positive ion) and anion (negative ion) in - 'A','B' & 'C'. Also identify P, Q, R, S, T, U, V, W.
a] Substance 'A' is water soluble and gives a curdy white precipitate 'P' with silver nitrate solution. 'P' is soluble in ammonium hydroxide but insoluble in dil. `HNO_3` . Substance 'A' reacts with ammonium hydroxide solution to give a white precipitate ' soluble in excess of `NH_4OH`.
b] A solution of substance 'B' is added to barium chloride solution. A white ppt. 'R' is formed, insoluble in dil. HCl or `HNO_3` . A dirty green ppt. 'S' is formed on addition of ammonium hydroxide to a solution of 'B' and the precipitate is insoluble in excess of ammonium hydroxide.
c] Substance 'C' is a coloured, crystalline salt which on heating decomposes leaving a black residue 'T'. On addition of copper turnings and conc. `H_2SO_4` to 'C' a coloured acidic gas 'U' is evolved on heating. A solution of'C' is added to NaOH soln. until in excess. A pale blue ppt. 'P' is obtained insoluble in excess of `NaOH` A solution of 'C' is then added to `NH_4OH` soln. in excess to give an inky blue solution 'V'. A solution of 'C' is warmed and hydrogen sulphide gas is passed through it. A black ppt. 'W' appears.