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

In the Geiger-Marsden experiment,which of the following is used to calculate the trajectory of the $\alpha$-particle?

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 . . . . . . .

An alpha particle is projected towards a stationary ${}_{92}^{235}U$ nucleus with $KE$ kinetic energy. Find the distance of closest approach.

The diagram shows the path of four $\alpha$-particles of the same energy being scattered by the nucleus of an atom. Which of these is/are not physically possible?

What is a head-on collision? For that,state the impact parameter.