Question

$1.86\text{g}$ of aniline completely reacts to form acetanilide. $10\%$ of the product is lost during purification. Amount of acetanilide obtained after purification in $\text{g}$ is $\times {10}^{-2}$.

Answer 1

$$\begin{array}{ccc}& & \\ PhN{H}_2& \to & PhNHCOC{H}_3\\ \left(C_6{H}_{7}N\right)& & \left(C_8{H}_{9}NO\right)\\ \text{Molar Mass=93}& & \text{Molar Mass=135}\end{array}$$
$93\text{g}$ aniline produces $135\text{g}$ acetanilide
$1.86\text{g}$ produce $135\times 1.86/93=2.70\text{g}$
At $10\%$ loss, $90\%$ product will be formed after purification.
$2.70\times 90\%=2.43=243\times {10}^{-2}\text{g}$.