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A first-order reaction takes 20 minutes for the concentration to fall from 1 M to 0.6 M. How long will it take for the concentration to fall from 0.6 M to 0.36 M?
- More than 20 min
- Less than 20 min
- Equal to 20 min
- Infinity
Correct answer: Equal to 20 min
Solution
First-order reactions need equal times for equal fractional decreases; since both steps reduce the concentration by the same factor (0.6), the second interval also takes 20 min.
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