Calculate the number of neutrons present in the nucleus of an element X which is represented as 31 15 X

Question

Calculate the number of neutrons present in the nucleus of an element X which is represented as ₁₅ X³¹ 

Answer 1

Mass number = No. of protons + No. of neutrons = 31 

∴ Number of neutrons = 31– number of protons 

                                    = 31–15 

                                    = 16