If halfe-life of a substance is 5 yrs, t...

If halfe-life of a substance is 5 yrs, then the total amount of substance left after 15 years, when initial amount is 64 grams is

A

16 grams

B

2 grams

C

32 grams

D

8 grams

Verified by Experts

The correct Answer is:

D

`t_(1//2) = 5 `yrs , t= 15 yrs
`therefore n = t/(t_(1//2)) = (15)/(5)= 3 `
Now `N = (N_0)/(2^n) = N_0/(2^3) = 1/8 N_0 = 1/8 xx 64 = 8 ` grams

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