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In a first order reaction the concentration of reactant decreases from 800 mol/dm 3 50 mol/dm 3 in 200 sec . The rate constant of reaction in s − 1 is

Options

  1. A2 × 10 − 4 s − 1
  2. B1.386 × 10 − 2 s − 1
  3. C3.45 × 10 5     s − 1
  4. D2 × 10 4   s − 1

Correct answer

B. 1.386 × 10 − 2 s − 1

Step-by-step solution

C t   =   C 0 2 n 2 n = 800 50 =16 2 n = 2 4 So, n   =   4 4T 1 2   =   200   sec T 1 2   =   50   sec K   =   0 .693 T 1 2   =   0 .693 50   =   1 .386   ×   10 − 2   sec − 1

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