Question

When $SO _{2}$ is passed through acidified solution of potassium dichromate, then chromium sulphate is formed. The change in valency of chromium is

• A. $+4$ to $+2$
• B. $+5$ to $+3$
• C. $+6$ to $+3$
• D. $+7$ to $+2$

Answer 1

Answer: (C)

$K _{2} Cr _{2} O _{7}+3 SO _{2}+4 H _{2} SO _{4} \rightarrow $
$K _{2} SO _{4}+ Cr _{2}\left( SO _{4}\right)_{3}+3 SO _{3}+4 H _{2} O$
O.N. of chrominum changes from $+6$ to $+3$