Question

Sodium salt $\left(A\right)$ of a dibasic acid $\stackrel{HCl}{\to }$ gas $\left(B\right)$

Gas $\left(B\right)$ turns $K_{2}C{r}_2{O}_7$ green and also lime water milky. Identify $\left(A\right)$ ?

• A. $N{a}_{2}O$
• B. $N{a}_{2}S{O}_3$
• C. $N{a}_{2}S{O}_4$
• D. None of these

Answer 1

The correct option is B $N{a}_{2}S{O}_3$

The sodium salt of dibasic acid is $N{a}_{2}S{O}_3$. It reacts with HCl to form $S{O}_2$ gas.

$N{a}_{2}S{O}_3$ $\stackrel{HCl}{\to }$ $NaCl+H_{2}O+S{O}_2\left(gas\right)$

Gas $S{O}_2$ turns $K_{2}C{r}_2{O}_7$ green and also turns lime water milky.

$3S{O}_2+K_{2}C{r}_2{O}_7+H_{2}S{O}_4\to K_{2}S{O}_4+C{r}_2\left(S{O}_4{)}_3\right(green)+H_{2}O$

Option (B) is correct.