JEE Main 2026 — Chemical Kinetics Question with Solution
JEE Main 2026 (23 January Shift 1)
Question
For the thermal decomposition of reactant , the following plot is constructed.
The half life of the reaction is ' . min. (Nearest integer)
The half life of the reaction is ' . min. (Nearest integer)
Enter your answer
Show full solutionCorrect answer: 10
Correct answer
10
Step-by-step explanation
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.
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.
Practice this on the real CBT interface
Solve this JEE Main question (and the rest of the Chemical Kinetics chapter) on PrepSharp's TCS iON-style CBT player — with timer, bookmarks and session analytics.
Solve interactively →About this question
This is a previous-year question from JEE Main 2026, covering the Chemical Kinetics chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.