A dipositive ion has an electronic arrangement $2,8,8$. Find out the number of electrons, protons, and neutrons in that element if its mass number is 40.

The correct option is A $20,20,20$
Number of electrons in the dipositively charged cation are 18.

So protons will be 20 and number of neutrons will be $40-20=20$.

Therefore number of protons, neutrons and electrons in the element are 20, 20 and 20 respectively.

Therefore, option B is correct.