Answer: Option (a) is the correct answer.
Explanation:
Atomic number means the sum of total number of protons acquired by an atom.
So, when atomic number of nitrogen is 7 then it means there are 7 protons present.
Whereas atomic mass means the sum of total number of protons and neutrons present in an atom.
Therefore, nitrogen-15 is an isotope of nitrogen that will always have 7 protons when it is neutral in nature. Hence, in nitrogen-15 the number of protons and neutrons are calculated as follows.
Atomic mass = no. of protons + no. of neutrons
15 = 7 + no. of neutrons
no. of neutrons = 15 - 7
= 8
Thus, we can conclude that the atomic nucleus of nitrogen-15 contains 8 neutrons.
