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For the reaction 2A + B -> products, doubling both [A] and [B] raised the rate from 0.3 to 2.4 mol L⁻¹ s⁻¹, while doubling only [A] raised the rate from 0.3 to 0.6 mol L⁻¹ s⁻¹. Which statement is correct?

1. Order of the reaction with respect to B is 2
2. Order of the reaction with respect to A is 2
3. Total order of the reaction is 4
4. Order of the reaction with respect to B is 1

Correct answer: Order of the reaction with respect to B is 2

Solution

Doubling A gives factor 2 so order in A = 1; doubling both gives factor 8 = 2³, so 2^(a+b) = 8 with a=1 gives b=2, order in B = 2.

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