When a salt is treated with sodium hydroxide solution,it gives gas $X$. On passing gas $X$ through reagent $Y$,a brown-coloured precipitate is formed. $X$ and $Y$ respectively,are

When $H_2S$ is passed through a mixture containing $Cu^{2+}$,$Ni^{2+}$,and $Zn^{2+}$ in an acidic solution,which ion will precipitate?

Which of the following ions form precipitates when $H_2S$ gas is passed through an acidic mixture containing $Cu^{2+}, Ni^{2+},$ and $Zn^{2+}$?

$A$ metal salt gives a yellow precipitate with potassium chromate in acetic acid and a white precipitate with dilute sulfuric acid,but it does not give a precipitate with sodium chloride or sodium iodide. What will be the composition of the white precipitate formed when sodium carbonate is added to the solution of this metal salt?

The reagent that can distinguish between silver and lead salt is

Among the following cations,the number of cations which will give characteristic precipitate in their identification tests with $K_4[Fe(CN)_6]$ is :
$Cu^{2+}, Fe^{3+}, Ba^{2+}, Ca^{2+}, NH_4^{+}, Mg^{2+}, Zn^{2+}$