Chromyl chloride vapour from the test is passed into aqueous NaOH to give a yellow solution via CrO2Cl2 + 4OH- -> CrO4^2- + 2Cl- + 2H2O. The oxidation states of Cr in CrO2Cl2 and in the yellow ion are respectively

JEE Main levelSingle correct optionDifficulty 2 of 3qa211

Chromyl chloride vapour from the test is passed into aqueous $NaOH$ to give a yellow solution via $CrO X_{2} Cl X_{2} + 4 OH X^{-} CrO X_{4} X^{2 -} + 2 Cl X^{-} + 2 H X_{2} O$ . The oxidation states of Cr in $CrO X_{2} Cl X_{2}$ and in the yellow ion are respectively

CrO X_{2} Cl X_{2}

x + 2 (- 2) + 2 (- 1) = 0

gives

x = + 6

. In

CrO X_{4} X^{2 -}

x + 4 (- 2) = - 2

gives

x = + 6

. The conversion is a hydrolysis, not a redox reaction, and the yellow chromate can be confirmed with lead acetate as yellow

PbCrO X_{4}