Question

Sulphite on treatment with dil. $H_{2}S{O}_4$ liberates a gas which:

• A. turns lead acetate paper black
• B. burns with blue flame
• C. smells like vinegar
• D. turns acidified $K_{2}C{r}_2{O}_7$ paper green

Answer 1

Answer: (D)

turns acidified $K_{2}C{r}_2{O}_7$ paper green

$K_{2}C{r}_2{O}_7$ ( orange yellow)) $+H_{2}S{O}_4+3S{O}_2\to K_{2}S{O}_4+C{r}_2(S{O}_4{)}_3$ (green) $+H_{2}O$Sulphite on treatment with dil. $H_{2}S{O}_4$ liberates $S{O}_2$ gas , which on keeping near to paper dipped in acidified $K_{2}C{r}_2{O}_7$ solution turns the paper green.