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A first-order reaction is 75% complete in 72 minutes. Determine the time required for (i) 50% completion and (ii) 87.5% completion.
- 24, 96
- 36, 108
- 48, 120
- 72, 144
Correct answer: 36, 108
Solution
75% completion means two half-lives (each leaves half), so t1/2 = 36 min (=50% completion); 87.5% completion is three half-lives = 108 min.
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