Question

In the following reaction, $P$ gives two products $Q$ and $R$ each in $40\%$ yield.

If the reaction is carried out with $420mg$ of $P$ the reaction yields $108.8mg$ of $Q$. The amount of $R$ produced in the reaction is closest to

• A. 97.6 mg
• B. 108.8 mg
• C. 84.8 mg
• D. 121.6 mg

Answer 1

Answer: (C)

Number of moles of P $=\frac{420\times 10^{-3}}{210}$
$=2\times 10^{-3}$
Number of moles of $Q$ and $R=40\%$ of
$P=\frac{40}{100}\times 2\times 10^{-3}$
$=8\times 10^{-4}$
mass of

$=8\times 10^{-4}\times 10^6=84.8\times 10^{-3}$
$=84.8mg$

$=8\times 10^{-4}\times 136$
$=108.8\times 10^{-3}$
$=108.8mg$
which is $Q$
$\therefore$ Mass of $R=84.8mg$