Question

An atom having atomic mass number 13 has 7 neutrons. What is the atomic number of the atom?

Answer 1

atomic number of the atom =mass number -number of neutrons

                                         =13-7=6

the atomic number of the atom is 6

Answer 2

Atomic mass number = 13
No. of neutrons = 7
atomic number= no. of protons inside
atomic number = mass number - number of neutrons
therefore, 13 - 7 =6