Which contribution added to rutherford's discovery of a positive nucleus?
a: electrons are scattered in an atom.
b: neutrons are inside the nucleus of an atom.
c: atoms of the same element have the same properties.
d: atoms are indivisible.

A: Electrons are scattered in an atom.

Explanation:

Ernest Rutherford performed the gold foil experiment which gave a deeper perspective into what an atom really is. In his experiment, he bombarded a thin gold foil with an alpha particle source.

From the behavior of the alpha particles that associated with the gold foil, a number of conclusions were drawn:

the answer is definitely c.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.