Calculate the atomic mass of nitrogen if the two common isotopes of nitrogen have masses of 14.003 amu (99.63% abundance) and 15.000 amu (0.37% abundance).

(99.63/100 x 14.003) + (0.37/100 x 15)

13.9511889 + 0.0555 = 14.0066889amu

13.95 + 0.0555 = 14.0055 (same thing just rounded numbers)

(You can round that to 14amu)

Answer is 14 amu

Ithink it’s 3 as the answer.