JEE Advanced Model Paper 6 with solutions for online practice

Given TA = 1 hour and TB = 2 hours , At t = 0 number of atoms of A = number of atoms of B = N0
∴ Number of atoms of A after 2 hours (i.e. after 2 half lives of A) is
NA = N0(

1

2

)2 =

N0

4

Number of atoms of B after 2 hrs (i.e. after 1 half life of B) is
NB =

N0

4

Now |R| = λN =

0.696N

T

Therefore
RA =

0.693NA

TA

and RB =

0.693NB

TB

∴

RA

RB

=

NA

NB

×

TB

TA

=

N0∕4

N0∕2

×

2

1

= 1