A radioactive element has half-life period of 30 days. How much of it will be left after 90 days?

Explanation

Total time = 90 days
Half life `(t_(1//2)) = 30` days
We know that
We know that
Total time `= n xx t_(1//2)`
So, `90 = n xx 30`
`n = 3`
Thus, quantity left after three half-life periods
`= ((1)/(2))^(3) N_(0)` [`N_(0) =` original amount]
` = (1)/(8) xx N_(0) = (1)/(8) N_(0)`