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JEE Main Physics Class 12 Atoms and Nuclei Part 1 Questions
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© examsnet.com
Question : 44
Total: 100
A piece of bone of an animal from a ruin is found to have
14
C
activity of 12 disintegrations per minute per
g
m
of its carbon content. The
14
C
activity of a living animal is 16 disintegrations per minute per
g
m
. How long ago nearly did the animal die? (Given half life of
14
C
is
t
1
∕
2
=
5760
years)
[Online April 12, 2014]
1672 years
2391 years
3291 years
4453 years
Validate
Solution:
Given, for
14
C
A
0
=
16
dis
min
−
1
g
−
1
A
=
12
dis
min
−
1
g
−
1
t
1
∕
2
=
5760
years
Now,
λ
=
0.693
t
1
∕
2
λ
=
0.693
5760
per year
Then, from,
t
=
2.303
λ
log
10
A
0
A
=
2.303
×
5760
0.693
log
10
16
12
=
2.303
×
5760
0.693
log
10
1.333
=
2.303
×
5760
×
0.1249
0.693
=
2390.81
≈
2391
years.
© examsnet.com
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