What is the percentage of $\alpha$-particles that have more than $1^o$ scattering in the Geiger-Marsden experiment (in $\%$)?

How is an atom represented? Why?

The $\alpha$-particle is the nucleus of an atom of

When an $\alpha$-particle of mass $m$ moving with velocity $v$ bombards a heavy nucleus of charge $Ze$,its distance of closest approach from the nucleus depends on $m$ as

An $\alpha$-particle of $5 \; MeV$ energy strikes a stationary uranium nucleus at a scattering angle of $180^o$. The distance of closest approach of the $\alpha$-particle to the nucleus will be of the order of:

When $\alpha$-particles with kinetic energy $\frac{1}{2} mv^2$ are bombarded on a heavy nucleus of charge $Ze$,the distance of closest approach is proportional to .........