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The decomposition of compound A in solution follows first order kinetics. A 10% w/v solution of A is 10% decomposed in 10 minutes at 10 deg C. To what percentage is a 20% w/v solution of A decomposed in 20 minutes at 10 deg C?
- 19
- 20
- 10
- 21
Correct answer: 19
Solution
First order rate is concentration-independent in fractional terms; 10% decomposes in 10 min means 90% remains, so in 20 min the fraction remaining is 0.9² = 0.81, i.e. 19% decomposed.
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