Slope of a curve Y plotted against X is mathematically given as

now here we can see that if similarly graph is plotted against distance and time then slope is given as

here we can say that above is ratio of small distance and very small interval of time.
so here we can say that this ratio of distance and time for very small interval of time is known as instantaneous speed of the object which is falling freely under gravity.
So here slope of the graph will represent the speed at a given instant.
Protons and neutrons have similar mass
Electrons are smaller then a proton or a neutron
The kinetic energy K given to the helium nucleus is equal to its potential energy, which is

where q=2e is the charge of the helium nucleus, and

is the potential difference applied to it.
Since we know the kinetic energy, we have

and from this we can find the potential difference: