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The radioactive isotope of caesium - 137...

The radioactive isotope of caesium - 137 of weight 8 g was collected on 1st February, 2006 and kept in a sealed tube. On 1st July 2006 it was found that only 0.25 g of it remained. The half-life period of the isotope is

A

a) 37.5 day

B

b) 30 day

C

c) 25 day

D

d) 50 day

Text Solution

Verified by Experts

The correct Answer is:
B
Cs-137 = 8 g on Ist Feb 2006
0.25 g left on Ist July 2006
8 g reduces to 0.25 in `5x30` days
`T=nxxt_(1//2)`
150 days = `5xxt_(1//2)`
`t_(1//2)=(150)/(5)` days = 30 days
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