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JEE Main20262 April 2026Morning ShiftChemistryChemical KineticsActual

t_ 100 % is the time required for the 100 % completion of the reaction while t_ 1/2 is the time required for 50 % of the reaction to be completed. Which of the following option correctly represents the relation between t_ 100 % and t_ 1/2 for zero and first order reactions respectively?

Options

  1. At_ 100 % = (t_ 1/2 )^2 and t_ 100 % = (t_ 1/2 )^ -
  2. Bt_ 100 % = 2t_ 1/2 and t_ 100 % = (t_ 1/2 )^
  3. Ct_ 100 % = 2t_ 1/2 and t_ 100 % = (2t_ 1/2 )^2
  4. Dt_ 100 % = (t_ 1/2 )^ and t_ 100 % = 2t_ 1/2

Correct answer

B. t_ 100 % = 2t_ 1/2 and t_ 100 % = (t_ 1/2 )^

Step-by-step solution

For a zero-order reaction: The integrated rate law is given by t = [A]₀ - [A]_t k . For 50 % completion ( t_ 1/2 ), [A]_t = [A]₀ 2 : t_ 1/2 = [A]₀ - [A]₀ 2 k = [A]₀ 2k For 100 % completion ( t_ 100 % ), [A]_t = 0 : t_ 100 % = [A]₀ - 0 k = [A]₀ k Comparing the two, we get: t_ 100 % = 2t_ 1/2 For a first-order reaction: The integrated rate law is given by t = 1 k ( [A]₀ [A]_t ) . For 100 % completion ( t_ 100 % ), [A]_t = 0 : t_ 100 % = 1 k ( [A]₀ 0 ) = A first-order reaction takes infinite time for 100 % completion.

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