The phosphate radical reacts with ammonium molybdate to form a precipitate of which color?

$A$ substance reacts with dilute $H_2SO_4$ to release a colorless gas,which turns baryta water $[Ba(OH)_2]$ turbid and decolorizes an acidic solution of dichromate. The presence of which of the following is indicated by this reaction?

White heavy precipitates are formed when $BaCl_2$ is added to a clear solution of compound $A$. Precipitates are insoluble in dilute $HCl$. Then,the compound $A$ is

When chlorine water is added to an aqueous solution of potassium halide in the presence of chloroform,a violet colour is obtained. On adding more chlorine water,the violet colour disappears,and a colourless solution is obtained. This test confirms the presence of which of the following in the aqueous solution?

Sodium sulphite on heating with dilute $HCl$ liberates a gas which

Which anion's aqueous solution gives a white precipitate with $AgNO_3$,which is soluble in excess $NH_4OH$?