Question

$\left[X\right]+dil. \, \text{H}_{2}SO_{4} \rightarrow \left[Y\right]$ colourless suffocating gas, $\left[Y\right]+K_{2}Cr_{2}O_{7}+H_{2}SO_{4} \rightarrow $ green colouration of solution. Then, $\left[X\right]$ and $\left[Y\right]$ are

• A. $SO_{3}^{2 -},SO_{2}$
• B. $Cl^{-},HCl$
• C. $S^{2 -},H_{2}S$
• D. $CO_{3}^{2 -},CO_{2}$

Answer 1

Answer: (A)

$\underset{X}{S O_{3}^{2 -}}+dil. \, \text{H}_{2}SO_{4} \rightarrow \underset{Y}{S O_{2}}+H_{2}O+SO_{4}^{2 -}$
Green colouration on reaction with $K_{2}Cr_{2}O_{7}$ and $H_{2}SO_{4}$ shows that Y is $SO_{2}$ .