Answer to Question 1
D,
The Coulomb force dominates in scattering experiments at lower energies, and within the Coulomb force only the massive, positive nucleus of the target interacting with the alpha particle determines the scattering angle.
Answer to Question 2
C.
The Franck-Hertz experiment involved colliding accelerated electrons and atoms in a gas, thereby exciting the atoms when the electrons give up some kinetic energy. The experiment showed that transitions of electrons to higher energy states are quantized and in calculable intervals.