a) $V_{nguyên\ tử} = \dfrac{4}{3}.\pi . (1,35.10^{-10})^3 = 1,03.10^{-29}(m^3)$
$m_{nguyên\ tử} = 65.1,6605.10^{-27} = 1,08.10^{-25}(kg)$
$\Rightarrow D_{nguyên\ tử} = \dfrac{m}{V}$ \(=\dfrac{1,08.10^{-25}}{1,03.10^{-29}}=10485\) $(kg/m^3)$
b)
$V_{hạt\ nhân} = \dfrac{4}{3}. \pi . (2.10^{-15})^3 = 3,35.10^{-44}(m^3)$
$D_{hạt\ nhân}$ \(=\dfrac{1,08.10^{-25}}{3,35.10^{-44}}=3,22.10^{18}\) $(kg/m^3)$