Answer:
The correct answer is - 10400 years.
Explanation:
Half-life an element is the time required to decay the half amount of the initial amount of the element.
Here, the initial amount n(i) = 100 gm
remained amount n(r) = 25 gm
then n =?
The formula for the calculating initial amount
n(i)=n(r)⋅2^n
n(i)=n(r)⋅2^n
n(i)/n(r) =2^n
puting value,
100/25 = 2^n
2^n = 4
n = 2
so to decay this amount there is two half life cycles involved,
Thus, time = 2*5700
= 10400 years.
