Question

A white crystalline salt $A$ reacts with dilute $HCl$ to liberate a suffocating gas $B$ and also forms a yellow precipitate. The gas $B$ turns potassium dichromate acidified with dilute $H_2SO_4$ to a green coloured solution $C, A, B$ and $C$ are respectively

• A. $Na_2S_2O_3, SO_2, Cr_2(SO_4)_3$
• B. $Na_2SO_3, SO_2, Cr_2(SO_4)_3$
• C. $Na_2SO_4, SO_2, Cr_2(SO_4)_3$
• D. $Na_2S, SO_2, Cr_2(SO_4)_3$

Answer 1

Answer: (A)

$Na_2S_2O_3, SO_2, Cr_2(SO_4)_3$

Answer 2

Gas $B$ turns the colour of acidified $K _{2} Cr _{2} O _{7}$ green thus it is $SO _{2}$ and $SO _{2}$ is obtained along with yellow precipitate when thio sulphate is treated with dilute acids. Thus, $A$ is $Na _{2} S _{2} O _{3}, B$ is $SO _{2}$ and $C$ is $Cr _{2}\left( SO _{4}\right)_{3}$. The reactions are as follows