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A radioactive isotope has a half-life of...

A radioactive isotope has a half-life of 20 days. If 100 g of the substance is taken, the weight of the isotope remaining after 40 days is

A

25 g

B

2.5 g

C

60 g

D

40 g

Text Solution

Verified by Experts

The correct Answer is:
A
`n = (40)/(20)= 2 `
`therefore ` Amount left `(N_0)/(2^n) = (100)/(2^2) = 25 g `
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