MCQ
During the qualitative analysis of $SO _3^{2-}$ using dilute $H _2 SO _4, SO _2$ gas is evolved which turns $K _2 Cr _2 O _7$ solution (acidified with dilute $H _2 SO _4$ ):
- ABlack
- BRed
- ✓Green
- DBlue
✓
Answer
Correct option: C.
Green
c
$Cr _2 O _7^{2-}+ SO _3^{2-} \stackrel{ H ^{+}}{\longrightarrow} \underset{\text { Green }}{ Cr ^{3+}}+ SO _4^{2-}$
$Cr _2 O _7^{2-}+ SO _3^{2-} \stackrel{ H ^{+}}{\longrightarrow} \underset{\text { Green }}{ Cr ^{3+}}+ SO _4^{2-}$
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