Question

which are different forms of an element that have different numbers of neutrons?
ions
isotopes
compounds
molecules

Explanation:

• Ions are atoms with a net charge (due to electron gain/loss), not related to neutron number.
• Isotopes are defined as atoms of the same element with the same number of protons but different numbers of neutrons.
• Compounds are substances made of two or more different elements, not about neutron variation in a single element.
• Molecules are groups of atoms (can be same or different elements) bonded together, not about neutron differences in an element.

Answer:

B. isotopes