Atoms with the same number of protons but different numbers of neutrons are called
a. isotopes.
b. ions.
c. chemical elements.
d. subatomic particles.

A. Isotopes

Explanation:

Let us look at the definition of each of the terms mentioned before answering the question.

Isotopes - An isotope of a chemical element is an atom that has a different number of neutrons (that is, a greater or lesser atomic mass) than the standard for that element. The atomic number is the number of protons in an atom's nucleus.

Ions - An ion is an atom or molecule that has a net electrical charge.

Chemical element - A chemical element is a species of atom having the same number of protons in their atomic nuclei (that is, the same atomic number, or Z). For example, the atomic number of oxygen is 8, so the element oxygen describes all atoms which have 8 protons.

Sub atomic Particles - subatomic particles are particles that are smaller than atoms. These may be composite particles, such as the neutron and proton.

Among the definitions, we can tell that only isotopes have atoms with same number of protons but different number of neutrons.

a compound is a molecule made of atoms from different elements.

a. by the combination of an unlimited number of elements

c, liquids evaporate, creating a gas