JEE Main 2021ChemistryChemical KineticsMediumNumerical

JEE Main 2021 — Chemical Kinetics Question with Solution

JEE Main 2021 (20 Jul Shift 2)

Question

PCl5g→PCl3g+Cl2g

In the above first order reaction the concentration of PCl5 reduces from initial concentration 50 mol L-1 to 10 mol L-1 in 120 minutes at 300 K. The rate constant for the reaction at 300 K is x×10-2 min-1. The value of x is __________.

[Given log5=0.6989]

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Correct answer
1

Step-by-step explanation

PCl5gI order 300 KPCl3g+Cl2g

t=0, [PCl5]=  50Mt=120 min, [PCl5]=  10M

t=120 min10M

⇒K=2.303tlogA0At

⇒K=2.303120log5010

⇒K=2.303120×0.6989=0.013413 min-1

=1.3413×10-2 min-1

1.34⇒ Nearest integer =1

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About this question

This is a previous-year question from JEE Main 2021, covering the Chemical Kinetics chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.