`10 gm` of radioactive material of half-life `15` year is kept in store for `20` years, The disintegrated material is.

Options

A. `12.5 g`
B. `10.5 g`
C. `6.03 g`
D. `4.03 g`

Answer

C

Explanation

( c) Remaining material `N = (N)/(2^(t//T))`
`rArr N = (10)/((2)^(20//15)) = (10)/(2.15) = 3.96 gm`
So decayed material `= 10 - 3.9 = 9.04 gm`.