Given, weight = 18.6 g

Here, 1 mole of aniline gives 1 mole of acetanilide

$$\therefore$$ mole of aniline = mole of acetanilide

$$\Rightarrow$$ $${{1.86} \over {93}} = {{{W_\text{Acetanilide}}} \over {135}}$$

$${W_\text{Acetanilide}} = {{1.86 \times 135} \over {93}}g = 2.70g$$

But efficiency of reaction is 90% only.

Hence, mass of acetanilide produced $$ = 2.70 \times {{90} \over {100}}g = 2.43g = 243 \times {10^2}g$$

x = 243