cis-Cyclohexane-1,2-diol is treated with one equivalent of HIO4 and the product is then reduced with excess NaBH4 followed by dilute acid work-up. The final product is

JEE Advanced levelSingle correct optionDifficulty 3 of 3ro196

cis-Cyclohexane-1,2-diol is treated with one equivalent of $HIO X_{4}$ and the product is then reduced with excess $NaBH X_{4}$ followed by dilute acid work-up. The final product is

Periodate cleaves the ring C1-C2 bond to give hexanedial. Sodium borohydride then reduces both CHO groups to CH2OH, giving

HOCH X_{2} (CH X_{2}) X_{4} CH X_{2} OH

. The product is hexane-1,6-diol, not the starting diol.