JEE Main 2020 · 9 January · evening · Single correct · +4 / −1
In the figure shown below reactant A (represented by square) is in equilibrium with product B (represented by circle). The equilibrium constant is :
- (a) 1
- (b) 2
- (c) 8
- (d) 4
Answer and solution
Answer (b) 2
Solution
Chemistry ma’am · 3 steps
Count the circles and the squares, then K is products over reactants, B over A.
- Write K. For A ⇌ B, the law of mass action gives K = [B]/[A]. Both species are in the same box, so the volume cancels and you can use particle counts directly.
- Count particles. The box holds 6 squares (A) and 11 circles (B).
K = n_B/n_A = 11/6 ≈ 1.8
- So. K is close to 2, and 2 is the nearest option, so the answer is (b).
The idea to keep. In a picture question, count each species, put products on top and reactants below. When moles of gas are the same on both sides, the box volume cancels.
Answer from the NTA final answer key. Solution by PrepWiser.