a) r= 0,135 nm= 0,135 .10^-7 cm
\( V_{NT}= 4/3 \pi r^3= 4/3 \pi (0,135.10^{-7})^3=1,03.10^{-23}\)
\(m_{Zn}= 65.u=65.1,6605 .10^{-24}=1,08.10^{-22}\)
=> \(D_{NT}=\dfrac{{1,08.10^{-22}}}{{1,03.10^{-23}}}=10,47g/cm^3\)
b)
\( V_{NT}= 4/3 \pi r^3= 4/3 \pi (2.10^{-13})^3=3,35.10^{-38}\)
\(m_{Zn}= 65.u=65.1,6605 .10^{-24}=1,08.10^{-22}\)
=> \(D_{NT}=\dfrac{{1,08.10^{-22}}}{{3,35.10^{-38}}}=3,22.10^{15}g/cm^3\)