Answer
100 m
Work Step by Step
Diameter of proton (nucleus): $1\times 10^{-15}$ m
Diameter of hydrogen atom: $1\times 10^{-10}$ m
$\frac{d_{atom}}{d_{nucleus}}=\frac{1\times 10^{-10}}{1\times 10^{-15}}=10^5.$
So the atom is about $100,000$ larger than its nucleus.
If the nucleus is modeled as $1$ mm ($=1\times 10^{-3}$ m, we have:
$d_{atom}=10^5\times 1\times 10^{-3}=100$.
So if the nucleus has a diameter of 1 mm, the diameter of atom will be :
100 m.
