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JEE Main 20204 SeptemberMorning Shift
Exam
JEE Main
Year
2020
Date
4 September
Shift
Morning Shift
Subject
Chemistry
Chapter
Chemical Kinetics

JEE Main 2020 · 4 September · Morning Shift · Chemistry · Chemical Kinetics

If 75% of a first order reaction was completed in 90 minutes, 60%...

If 7575% of a first order reaction was completed in 9090 minutes, 6060% of the same reaction would be completed in approximately (in minutes) _____
(Take: log⁡2=0.30;log⁡2.5=0.40\log 2 = 0.30; \log 2.5 = 0.40)

Correct answer

0

Step-by-step solution

T = \dfrac{2 .303}{K}\log \left[\dfrac{100}{100 - x %}\right]

{T}_{75 %} = \dfrac{2 .303}{K}\log \left[\dfrac{100}{25}\right] = 90

{T}_{60 %} = \dfrac{2 .303}{K}\log \left[\dfrac{100}{40}\right]

\dfrac{{T}_{75 %}}{{T}_{60 %}} = \dfrac{2\log 2}{\log 2 .5} ⇒⇒ \dfrac{90}{{T}_{60 %}} = \dfrac{2 \times 0 .3}{0 .4}

{T}_{60 %} = \dfrac{90 \times 4}{6} = 60min.

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