Each molecule of acetic anhydride transfers one acetyl group to one OH group. Sucrose, C12H22O11, has eight OH groups. The moles of acetic anhydride needed to acetylate 0.5 mol of sucrose completely are

JEE Advanced levelSingle correct optionDifficulty 3 of 3bm049

Each molecule of acetic anhydride transfers one acetyl group to one OH group. Sucrose, $C X_{12} H X_{22} O X_{11}$ , has eight OH groups. The moles of acetic anhydride needed to acetylate 0.5 mol of sucrose completely are

Sucrose octaacetate needs 8 acetyl groups per molecule. For 0.5 mol,

0.5 \times 8 = 4

mol of acetic anhydride. The value 8 is for 1 mol, and 5.5 wrongly counts the oxygen atoms.