What is impact parameters for scattering by `180^@`?

Define impact parameter?

What is the impact parameter at which the scattering angle is 90^@ of rZ=79 and alpha particle of initial kinetic energy of 10 MeV.

How is impact parameter related to the scattering angle?

Name three gas parameters.

State rayleigh's law of scattering.

explain about parameters of growth?

Calculate the impact parameter of 5 MeV alpha particle scattered by 10^@ ,when it approaches a gold nucleus.

Why is gold foil preffered on scattering object in rutherford's experiment?