Nuclear Physics And Radioactivity Question 290
Question: If 20 gm of a radioactive substance due to radioactive decay reduces to 10 gm in 4 minutes, then in what time 80 gm of the same substance will reduce to 10 gm [MP PMT 1994]
Options:
A) In 8 minutes
B) In 12 minutes
C) In 16 minutes
D) In 20 minutes
Show Answer
Answer:
Correct Answer: B
Solution:
20 gm substance reduces to 10 gm (i.e. becomes half in 4 min. So $ {T_{1/2}}=4,\min $ . Again $ M=M_{0}{{( \frac{1}{2} )}^{t/{T_{1/2}}}} $
Þ $ 10=80,{{( \frac{1}{2} )}^{t/4}} $
Þ $ \frac{1}{8}={{( \frac{1}{2} )}^{3}}={{( \frac{1}{2} )}^{t/4}} $
Þ t = 12 min.
BETA
