Radon `(Ra)` decays into Polonium `(P_0)` by emitting an `alpha-`particle with half-life of `4` days. A sample contains `6.4 xx 10^10` atoms of `R_n`. After `12` days, the number of atoms of `R_n` left in the sample will be

Options

A. `3.2 xx 10^(10)`
B. `0.53 xx 10^(10)`
C. `2.1 xx 10^(10)`
D. `0.8 xx 10^(10)`

Answer

D

Explanation

12 days `= 3T_(1//2)`
Number of nuclei remaining
`= (N_(0))/(2^(n)) = (6.4 xx 10^(10))/(2^(3))= 0.8 xx 10^(10)`