Which source is associated with a line emission spectrum?

What is shown by Thomson's experiments of electric discharge through gases? And explain the plum pudding model.

In the Geiger-Marsden experiment, the number of scattered $\alpha$-particles $N(\theta)$ is plotted as a function of the scattering angle $\theta$. Which of the following options represents the correct plot?

$\alpha$-particles of energy $400 \, KeV$ are bombarded on a nucleus of $_{82}Pb$. In the scattering of $\alpha$-particles, what will be the minimum distance of approach from the nucleus?

Find the number of atoms in $39.4 \ g$ of gold. The molar mass of gold is $197 \ g \ mol^{-1}$.

The graph which depicts the results of the Rutherford gold foil experiment with $\alpha$-particles is:
$\theta$: Scattering angle
$Y$: Number of scattered $\alpha$-particles detected
(Plots are schematic and not to scale)