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A → products (First order reaction) Three sets of experiment were performed for a reaction under similar experimental conditions. Run 1 = 100 mL of 10 M solution of reactant A Run 2 = 200 mL of 10 M solution of reactant A Run 3 = 100 mL of 10 M solution of reactant A + 100 mL of H2O added. The correct variation of rate of reaction is

1. Run 1 = Run 2 = Run 3
2. Run 3 < Run 1 = Run 2
3. Run 2 < Run 1 = Run 3
4. Run 1 < Run 2 < Run 3

Correct answer: Run 3 < Run 1 = Run 2

Solution

In a first-order reaction, the rate depends on the concentration of the reactant. In Run 1 and Run 2, the concentration of A remains the same, leading to equal rates, while Run 3 has a diluted concentration due to the addition of water, resulting in a lower reaction rate.

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