In Rutherford's $\alpha$-particle scattering experiment,which of the following was discovered?

According to the Rutherford's atomic model,the electrons inside the atom are

The size of an atom is of the order of:

The distance of the closest approach of an alpha particle fired at a nucleus with kinetic energy $K$ is $r_{0}$. The distance of the closest approach when the $\alpha$-particle is fired at the same nucleus with kinetic energy $2K$ will be . . . . . . .

What does it mean if the $\alpha$-particle passes through the gold foil without any deviation?

In the Rutherford scattering experiment,what will be the correct scattering angle $\theta$ for an $\alpha$-particle with an impact parameter $b = 0$ (in $^o$)?