Question
For the thermal decomposition of reactant AB ( g ), the following plot is constructed. The half life of the reaction is ' x^ . x= \_\_\_\_ min. (Nearest integer)
JEE Main
Chemistry
Chemical Kinetics
2026
JEE Main 2026 (23 January Shift 1)
JEE Main Chemistry Question (2026) — Solution
Options
- A. A
- B. B
- C. C
- D. D
Answer
A. A
Step-by-step solution
From the concentration vs. time graph, the thermal decomposition of AB(g) shows a linear decrease in concentration, indicating zeroth-order kinetics. Initial concentration: [AB]₀ = 0.6 M at t = 0 s. Reading from the graph: [AB] = 0.5 M at t = 200 s. Rate of decomposition: Δ[AB]/Δt = (0.6 - 0.5) M / 200 s = 0.0005 M/s. For zeroth-order kinetics: [AB] = [AB]₀ - kt. Half-life occurs when [AB] = [AB]₀/2 = 0.3 M. 0.3 = 0.6 - 0.0005 × t₁/₂. t₁/₂ = 0.3 / 0.0005 = 600 s = 10 min.
Related: Chemistry — Chemical Kinetics · All PYQ Banks