<span>An isotope is a form of a
chemical element whose atomic nucleus contains a specific number of neutrons in
addition to the number of protons that distinctively defines the element. The
nuclei of most atoms have neutrons as well as protons.</span>
Answer:

Explanation:
The energy difference between the energy levels involved in the transition of the electron is directly proportional to the frequency of the emitted photon:

Where h is the Planck constant. The photon's frequency is inversely proportional to its wavelegth:

Here c is the speed of light. Replacing (2) in (1):

Be heavier
density=mass÷volume
if two items have the same size they have the same volume so the heavier one will be the denser one