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AP EAMCET202124 Aug 2021Evening ShiftChemistryChemical KineticsActual

If the rate constant for a first order reaction is k , then find the time required for completion of 80 % of the reaction.

Options

  1. A3.2 k
  2. B1.6 k
  3. C4.8 k
  4. D0.8 k

Correct answer

B. 1.6 k

Step-by-step solution

First order rate constant is given as k= 2.303 t [A₀ ] [A_t ] 80 % completed, then [A₀ ]=100A_t=100-80=20 aligned & k= 2.303 t 100 20 & k= 2.303 t 10 2 & k= 2.303 t ( 10- 2) & k= 2.303 t (1-0.3) & k= 2.303 0.7 t t= 1.6 k . aligned

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