Question

For the reaction $A+3B\rightleftharpoons 2C+D$, initial mole of $A$ is twice that of $B$. If at equilibrium moles of $B$ and $C$ are equal, then percent of $B$ reacted is:

• A. $10$%
• B. $20$%
• C. $40$%
• D. $60$%

Answer 1

The correct option is D $60$%

$A+3B\rightleftharpoons 2C+D$

A B C D

Initial conc a a/2 0 0

At equilibrium a-x (a/2) - 3x 2x x

(a/2)-3x = 2x

a/2 = 5x

x = a/10

Amount of B reacted =3x = 3a/10

Initial amt of B = a/2

$\therefore$ percentage of B reacted = $\frac{3a/10}{a/2}\ast 100=60\%$