What was the thickness of the gold foil used in the Geiger-Marsden scattering experiment?

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

Answer the following questions,which help you understand the difference between Thomson's model and Rutherford's model better.
$(a)$ Is the average angle of deflection of $\alpha$-particles by a thin gold foil predicted by Thomson's model much less,about the same,or much greater than that predicted by Rutherford's model?
$(b)$ Is the probability of backward scattering (i.e.,scattering of $\alpha$-particles at angles greater than $90^{\circ}$) predicted by Thomson's model much less,about the same,or much greater than that predicted by Rutherford's model?
$(c)$ Keeping other factors fixed,it is found experimentally that for small thickness $t$,the number of $\alpha$-particles scattered at moderate angles is proportional to $t$. What clue does this linear dependence on $t$ provide?
$(d)$ In which model is it completely wrong to ignore multiple scattering for the calculation of average angle of scattering of $\alpha$-particles by a thin foil?

$A$ beam of fast-moving alpha particles was directed towards a thin gold foil. The parts $A'$,$B'$,and $C'$ of the transmitted and reflected beams corresponding to the incident parts $A$,$B$,and $C$ of the beam are shown in the adjoining diagram. The number of alpha particles in:

An $\alpha$-particle of energy $4 \text{ MeV}$ is scattered through $180^\circ$ by a fixed uranium nucleus. The distance of the closest approach is of the order of

What radioactive source did Geiger and Marsden use in the scattering experiment?