What was ernest rutherford's contribution to our understanding of atomic structure?

a.) he discovered the existence of a center to the atom.

b.) he discovered the mass of the electron.

c.) he discovered the electron.

d.) he discovered the neutron.

A

Explanation:

A) He discovered the existence of a center to the atom.

Explanation:

Rutherford’s performed his gold foil scattering experiment. He made alpha particles to strike a gold foil from a radioactive source.

In his experiment, he found that most of the particles passed through the gold foil without showing any deflection. From this, he concluded that most of the space inside an atom is empty.

Some of the particles got deflected through small angles which shows the positive charge of the atom is in the center nucleus  

Very few particles deflected through large angles is due to the mass of the atom and the space occupied by it is very small.

Some of the alpha particles were deflected back through significant angles, this suggest that the centre of the atom must be tiny but contain a lot of mass and it was named nucleus by Ernest Rutherford

what are the choices?

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.