Question

An ion X2+ contain 18 electron and 20 neutrons. find the atomic number and mass number of element X

Answer 1

atomic no. = no. of protons
no. of electrons in x2+ ion. = 18
no. of electrons in x element = 20
therefore the no. of protons in x = 20
Therefore atomic no. = 20
mass of element x = protons + neutrons
= 20 + 20
= 40