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A substance undergoes a first-order decomposition. The decomposition follows two parallel first-order reactions as given below. The percentage distributions of B and C are ( k 1 = 1 . 26 × 10 - 4   s - 1 and k 2 = 3 . 8 × 10 - 5   s - 1 )

Options

  1. A80 %   B and 20 %   C
  2. B76 . 83 %   B and 23 . 17 %   C
  3. C90 %   B and 10 %   C
  4. D60 %   B and 40 %   C

Correct answer

B. 76 . 83 %   B and 23 . 17 %   C

Step-by-step solution

In the given parallel reaction, a reactant A is dissociating to produce two products B and C simultaneously as follows, Where k 1 = 1 . 26 × 10 - 4 s - 1 and k 2 = 3 . 8 × 10 - 5 s - 1 In a parallel reaction, the ratio of the concentrations of products at any time is equal to the ratio of the rate constant of their respective reactions, i.e., B C = k 1 k 2 Then, the percentage of B can be calculated as follows, % B = k 1 k 1 + k 2 × 100 % B = 1 . 26 × 10 - 4 1 . 26 × 10 - 4 + 3 . 8 × 1

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