NEET Chemistry Chemical Kinetics Questions Solved


A first order reaction takes 40 min for 30% decomposition.Calculate t1/2   

(A) 77.7 min.                                                  

(B) 27.2 min.

(C) 55.3 min.                                                 

(D) 67.3 min.

(A). Extent of reaction = 30%
Time taken = 40 min
For a first order reaction,

t=2.303klogaa-x=2.303klog11-x/a40 min 2.303klog11-0.3or k=2.303klog 10.7=8.92×10-3min-1

we know, for a first order reaction, t1/2=2.303 log 2k

then,t1/2=2.303 log 28.92×10-3min-1=77.7 min.

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