Answer:

Explanation:
As per energy conservation we know that the electrostatic potential energy of the charge system is equal to the initial kinetic energy of the alpha particle
So here we can write it as

now we know that


z = 79
here kinetic energy of the incident alpha particle is given as

now we have

now we have

Answer:
Inhibit the flow of electrons
Explanation:
An electric current usually consists of electrons moving through a wire.
An insulator prevents the flow of an electric current, so it inhibits the flow of electrons.
Answer:
An element is a pure substance and is made of only one type of atom.
Explanation:
It cannot be broken down into a simpler substance.