A radioactive substance has a mass of 16 mg and its half life is 25 years. The quantity of substance will remain to be disintegrated in 100 years is

Options

A. 1 mg
B. 2 mg
C. 5 mg
D. 7 mg

Answer

A

Explanation

Now `N/N_(0)=(1/2)^(n)` where `n=t/T`
Thus, `n=100/25=4`
`N/N_(0)=(1/2)^(4)`
`N/N_(0)=1/16`
`N=N_(0)/16=16/16=1` mg