On treating a compound with warm dil. $H_{2}SO_{4}$,gas $X$ is evolved which turns $K_{2}Cr_{2}O_{7}$ paper acidified with dil. $H_{2}SO_{4}$ to a green compound $Y$. $X$ and $Y$ respectively are

Given below are two statements:
Statement-$I$: The gas liberated on warming a salt with dil $H_2SO_4$,turns a piece of paper dipped in lead acetate into black,it is a confirmatory test for sulphide ion.
Statement-$II$: In statement-$I$ the colour of paper turns black because of formation of lead sulphite.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which of the following anions does not produce a precipitate with $BaCl_2$ solution,however,gives a precipitate with $AgNO_3$?

Sodium nitroprusside,when added to an alkaline solution of sulphide ions,produces a purple colour due to the formation of:

To an inorganic mixture,dilute $H_2SO_4$ is added in the cold; a colourless,odourless gas is evolved. The mixture contains:

Which of the following radicals does not liberate gas with ($Zn$ + dil. $HCl$) on warming?