Isotopes are atoms with same number of protons and electrons but different number of neutrons.

Isotopes are atoms with same number of protons and electrons but different number of neutrons.

• A. Different number of protons; same electrons
• B. Different number of electrons; same protons
• C. Same number of protons and electrons but different neutrons
• D. Same atomic mass but different charge

Answer: (C)

Isotopes are variants of the same element that share the same number of protons and, in a neutral atom, the same number of electrons, but differ in the number of neutrons. Because the mass number is protons plus neutrons, changing the neutron count changes the mass without altering the charge or the element’s identity. So the statement that fits is: same protons and electrons but different neutrons. Other options would imply a different element (different protons) or a different charge (different electron count) or keep the mass the same despite a change in neutrons, which doesn’t describe isotopes.

Isotopes are variants of the same element that share the same number of protons and, in a neutral atom, the same number of electrons, but differ in the number of neutrons. Because the mass number is protons plus neutrons, changing the neutron count changes the mass without altering the charge or the element’s identity. So the statement that fits is: same protons and electrons but different neutrons.

Other options would imply a different element (different protons) or a different charge (different electron count) or keep the mass the same despite a change in neutrons, which doesn’t describe isotopes.