Molar mass of aniline (C6H5NH2) = 93 g/mol.
Moles of aniline = 9.3/93 = 0.1 mol.
From the reaction, theoretical yield of acetanilide = 0.1 mol.
Molar mass of acetanilide (C6H5NHCOCH3) = 135 g/mol.
Theoretical mass = 0.1 × 135 = 13.5 g.
Percentage yield = (11/13.5) × 100 = 81.5%