JEE Main 2026 Chemistry question
For a first order reaction A → B:
| t/min | [A]/M | |---|---| | 0 | 0.6500 | | x | 0.0650 | | 20 | 0.00065 |
x = min. (Nearest integer)
Answer: 7
Solution
From t=0 to 20, [A] falls by a factor of 1000: k = ln(1000)/20 = 3ln10/20. At t=x, [A] falls by a factor of 10: x = ln10/k = 20/3 ≈ 7.