a,

$m=65u=65.1,6605.10^{-27}=1,08.10^{-25}(kg)$

$r=1,35.10^{-1}(nm)=1,35.10^{-1}.10^{-9}=1,35.10^{-10}(m)$

$V=\dfrac{4}{3}\pi.r^3=\dfrac{4}{3}\pi.(1,35.10^{-10})^3=1,03.10^{-29}(m^3)$

$\Rightarrow D_{Zn}=\dfrac{m}{V}=10485,43(kg/m^3)$

b,

$r_{\text{hạt nhân}}=2.10^{-6}.10^{-9}=2.10^{-15}(m)$

$\Rightarrow V_{\text{hạt nhân}}=\dfrac{4}{3}\pi.(2.10^{-15})^3=3,35.10^{-44}(m^3)$

$\Rightarrow D_{\text{hạt nhân}}=\dfrac{m}{V}=3,22.10^{18}(kg/m^3)$

Đáp án:

Giải thích các bước giải:

có : $r_{\text{nguyên tử Zn}} = 1,35.10^{-1}nm = 1,35.10^{-10}m$

$1u = 1,6605.10^{-27}(kg)$

$⇒ m_{Zn} = 65.1,6605.10^{-27} = 1,079.10^{-25}(kg)$

$V_{\text{nguyên tử Zn}}=\dfrac{4}{3}.\pi.r^3=\dfrac{4}{3}.\pi.(1,35.10^{-10})³= 1,03.10^{-29}(m^3)$

$⇒ D = \dfrac{m}{V} = \dfrac{1,079.10^{-25}}{1,03.10^{-29}} = 10475,8(kg/m^3)$