On heating $NaCl + K_2Cr_2O_7 + \text{conc. } H_2SO_4$,the gas evolved is:

Which of the following solutions will yield a black precipitate when $H_2S$ gas is passed through it?

$A$ salt on treatment with dil. $HCl$ gives a pungent smelling gas and a yellow precipitate. The salt gives a green flame when tested. The salt solution gives a yellow precipitate with potassium chromate. The salt is:

An inorganic compound $X$ on treatment with concentrated $H_{2}SO_{4}$ produces brown fumes and gives a dark brown ring with $FeSO_{4}$ in the presence of concentrated $H_{2}SO_{4}$. Also,compound $X$ gives a precipitate $Y$ when its solution in dilute $HCl$ is treated with $H_{2}S$ gas. The precipitate $Y$ on treatment with concentrated $HNO_{3}$ followed by excess of $NH_{4}OH$ further gives a deep blue coloured solution. Compound $X$ is:

Sodium carbonate cannot be used in place of ammonium carbonate for the precipitation of the fifth group radicals because

Which of the following is soluble in yellow ammonium sulphide?