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

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 . . . . . . .

Write the name of the scientist who suggested that matter is made up of atoms.

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

Choose the correct alternative from the clues given at the end of each statement:
$(a)$ The size of the atom in Thomson's model is .......... the atomic size in Rutherford's model. (much greater than/no different from/much less than.)
$(b)$ In the ground state of .......... electrons are in stable equilibrium,while in .......... electrons always experience a net force. (Thomson's model/Rutherford's model.)
$(c)$ $A$ classical atom based on .......... is doomed to collapse. (Thomson's model/Rutherford's model.)
$(d)$ An atom has a nearly continuous mass distribution in a .......... but has a highly non-uniform mass distribution in .......... (Thomson's model/Rutherford's model.)
$(e)$ The positively charged part of the atom possesses most of the mass in .......... (Rutherford's model/both the models.)

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