Respuesta :
To answer this you should know that the way the atomic mass is calculated when there are several isotopes is as the weighted average of the atomic masses of the several isotopes.
Given that there are only two isotopes and that their atomic masses are:
nitrogen - 14: 14.00 uma, and
nitrogen - 15: 15.00 uma
The only way that the weigthed average of tha atomis mass of the element is so close to 14 is that the nitrogen-14 is much more abundant than the nigrogen-15.
Answer: first option.
Given that there are only two isotopes and that their atomic masses are:
nitrogen - 14: 14.00 uma, and
nitrogen - 15: 15.00 uma
The only way that the weigthed average of tha atomis mass of the element is so close to 14 is that the nitrogen-14 is much more abundant than the nigrogen-15.
Answer: first option.