Question

Most of the mass in an atom is in the nucleus.
True
False

Answer 1

The answer you are looking for is true

Answer 2

There are "Protons" & "Neutrons" in an atom inside the nucleus. They are very massive as compared to "Electrons" (which reside outside the nucleus).So, the sentence is correct.

In short, Your Final answer would be "True"

Hope this helps!