Question

An ion (M²⁺) contain 10 electrons and 12 neutrons what is the atomic number and mass number of the element M.

Answer 1

Since, M²⁺ contains 10 electrons and the M²⁺ ion suggests that it has lost 2 electrons so it contains total 12 electrons. The number of electrons are equal to number of protons in an atom, so its atomic number is 12.

The no of protons and neurones is known as mass number which is 24 (12 + 12 = 24.)