Question

when two atoms of the same element have different masses, they are called ____, and have a different number of ____. neutrons; isotopes isotopes; neutrons atoms; isotopes isotopes; protons

Explanation:

Isotopes are atoms of the same element with different masses due to a varying number of neutrons. Protons define the element type, and changing the number of protons would result in a different element.

Answer:

B. Isotopes; Neutrons