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

A radioactive isotope has a half-life of 10 day. If today there are 125 g of left, what was the original mass 40 day earlier? a)600 g b)1000 g c)1250 g d)2000 g

A

2 g

B

600 mg

C

1 g

D

1.5 g

Text Solution

Verified by Experts

The correct Answer is:
A
`N = N_0 (1/2)^n * n = (40)/(10)= 4`
`(125)/(1000) = N_0 (1/2)^4 , N_0 = (125)/(1000) xx 2 xx 2 xx 2 xx2 = 2g `
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