Chromyl chloride vapours are passed into aqueous NaOH: CrO2Cl2 + 4NaOH -> Na2CrO4 + 2NaCl + 2H2O. The oxidation states of Cr in CrO2Cl2 and in Na2CrO4 and the nature of this step are respectively

JEE Main levelSingle correct optionDifficulty 2 of 3qa043

Chromyl chloride vapours are passed into aqueous NaOH: $CrO X_{2} Cl X_{2} + 4 NaOH Na X_{2} CrO X_{4} + 2 NaCl + 2 H X_{2} O$ . The oxidation states of Cr in $CrO X_{2} Cl X_{2}$ and in $Na X_{2} CrO X_{4}$ and the nature of this step are respectively

CrO X_{2} Cl X_{2}

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

gives

x = + 6

. In

Na X_{2} CrO X_{4}

2 (+ 1) + x + 4 (- 2) = 0

gives

x = + 6

. No element changes oxidation state, so this is hydrolysis and neutralisation, not redox. The yellow chromate is then confirmed by lead acetate.