JEE Main 2014 · 19 Apr · Shift 1 · Physics Q27

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PhysicsSingle correct+4 / -1Question 27 of 90

A piece of wood from a recently cut tree shows 20 decays per minute. A wooden piece of same size placed in a museum (obtained from a tree cut many years back) shows 2 decays per minute. If half life of C $^{14}$ is 5730 years, then age of the wooden piece placed in the museum is approximately :

10439 years

13094 years

19039 years

39049 years

Answer and worked solution

Official answer: C

The activity fell by a factor of 10:
$t=t_{1/2}\log_2 10=5730\times3.32\approx19039\text{ years}.$

Topics:Radioactive decay

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JEE Main 2014 · 19 Apr · Shift 1, Physics question 27