Question

The half-life period of a radioactive element is 140 days. After 560 days, one gram of the element will reduced to :(a) $\frac{1}{2} g$(b) $\frac{1}{4} g$(c) $\frac{1}{8} g$(d) $\frac{1}{16} g$

Answer 1

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Hello mate!!

Ur answer is option no . C

Answer 2

Let n is equal to the ratio of total time and half-life period, which is 

n=Total time / Half-life period = 560/140 =4. 

To determine the element reduction, 

N = N0(1/2)n 

N = N0(1/2)4 

N = N0/16 

N0 = 1 gram 

Therefore, one gram of the element will reduce to 1/16 of the original amount.