Question

In the chemical reaction $A+B\to AB;B$ is acting as a limiting reagent then choose the correct option.

AIIMS-MBBS-2019-26 May-Morning Q.80

• A. $\text{A = 50 atm, B = 100 atm}$
• B. $\text{A = 100 atm, B = 200 atm}$
• C. $\text{A = 50 atm, B = 200 atm}$
• D. $\text{A = 50 atm, B = 30 atm}$

Answer 1

The correct option is D $\text{A = 50 atm, B = 30 atm}$

A limiting reagent is a reactant which is present in proportionally less than the required quantity.
Now, it is given that $B$ is the limiting reagent which means it should be present in proportionally less quantity.
From the given chemical equation:
$A+B\to AB$
we can conclude that,
$1mol$ of $A$ requires $1mol$ of $B$ to undergo complete reaction.
And, since the options are in terms of partial pressures, we can assume both $A$ and $B$ to be gaseous.
In case of gases, reaction can be studied in terms of moles or volume or pressure.
So, for $B$ to be the limiting reagent, the partial pressure of $B$ should be less than the partial pressure of $A$.

Hence the correct answer is option (c).