Verified Solution • 2025–26 Session moderate

QNEET-2019-Ch-785: NEET 2019 Chemistry - Class 12 NEET-2019-Ch-785 Solution: If the rate constant for a first order reaction is k the time…

If the rate constant for a first order reaction is k the time (t) required for the completion of 99% of the reaction is given by: t=4.606kt = \frac{4.606}{k} t=2.303kt = \frac{2.303}{k} t=0.693kt = \frac{0.693}{k} t=6.909kt = \frac{6.909}{k}

Multiple Choice Options

  • A t=4.606kt = {{4.606} \over k} t = k 4.606 _
  • B t=2.303kt = {{2.303} \over k} t = k 2.303 _
  • C t=0.693kt = {{0.693} \over k} t = k 0.693 _
  • D t=6.909kt = {{6.909} \over k} t = k 6.909 _

Step-by-Step Verified Solution

For a first order reaction, t = 2.303 k log _ [ A 0 ] [ A ] for 99% completion of the reaction, t = 2.303 k log _ 100 100 _ 99 _ t = 4.606 k

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