JEE Main 2026 · 2 Apr · Shift 2 · Chemistry Q72

ChemistryInteger+4 / -1Question 72 of 75

Consider the following gas phase reaction being carried out in a closed vessel at 25 °C.
$\ce{2A(g) -> 4B(g) + C(g)}$

time (min)	total pressure of the system (mm Hg)
30	300
∞	600

The pressure of C(g) at 30 minutes time interval would be ________ mm Hg. (nearest integer)

Your answer

Answer and worked solution

Official answer: 20

Pressures. Start with $p_0$ of A; $2x$ of A reacts, forming $4x$ B and $x$ C. Total $=p_0+3x$ .

Complete reaction ( $2x=p_0$ ): total $=2.5p_0=600$ , so $p_0=240$ mm Hg.

At 30 min. $240+3x=300$ gives $x=20$ , so $p_\ce{C}=20$ mm Hg.

Answer: 20

JEE Main 2026 · 2 Apr · Shift 2, Chemistry question 72