Answer:
Since different isotopes of an element have different numbers of neutrons (but always the same number of protons) they have different mass numbers. Nitrogen-14 and nitrogen-15 are both stable isotopes of nitrogen. However, the other 5 isotopes are all unstable.
<span> E = h v where v = frequency h = plancks constant 6.626 * 10 - 34
4.8 * 6.626 = 31.8 </span>
Hey there!
The answer as well as the explanation is in the image attached. Let me know if there's anything you're unable to see.
Hope this helps!
It is A I took it befor hope this helps:)