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JEE Main levelSingle correct optionDifficulty 2 of 3df099

When $SO X_{2}$ is passed through an acidified solution of potassium dichromate, the observed colour change is

Aorange to colourless
Borange to green
Corange to yellow
Dorange to purple

Answer: B

Cr X_{2} O X_{7} X^{2 -} + 3 SO X_{2} + 2 H X^{+} \to 2 Cr X^{3 +} + 3 SO X_{4} X^{2 -} + H X_{2} O

. The orange dichromate is reduced to green

Cr X^{3 +}

, which is the standard test for

SO X_{2}

.

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