In Rutherford’s nuclear model of the atom, the nucleus (radius about \(10^{-15}~\text{m}\)) is analogous to the sun about which the electron move in orbit (radius \(\approx 10^{-10}~\text{m}\)) like the earth orbits around the sun. If the dimensions of the solar system had the same proportions as those of the atom, then: 
(the radius of the earth's orbit is about \(1.5\times 10^{11}~\text{m}\) and the radius of the sun is taken as \(7\times10^{8}~\text{m}\).)

In a Geiger-Marsden experiment, what is the distance of the closest approach to the nucleus of a \(7.7\text{ MeV}\) \(\alpha\)-particle before it comes momentarily to rest and reverses its direction?
1. \(10\text{ fm}\)
2. \(25\text{ fm}\)
3. \(30\text{ fm}\)
4. \(35\text{ fm}\)

It is found experimentally that \(13.6~\text{eV}\) energy is required to separate a hydrogen atom into a proton and an electron. The velocity of the electron in a hydrogen atom is:
1. \(3.2\times10^6~\text{m/s}\)
2. \(2.2\times10^6~\text{m/s}\)
3. \(3.2\times10^6~\text{m/s}\)
4. \(1.2\times10^6~\text{m/s}\)$\mathrm{}$