An element X has mass number 40 and contains 21 neutrons in its atom. To which group of the Periodic Table does it belong? HomePeriodic Table MCQsAn element X has mass number 40 and contains 21 neutrons in its atom. To which group of the Periodic Table does it belong?Q. An element X has mass number 40 and contains 21 neutrons in its atom. To which group of the Periodic Table does it belong?A. Group 1B. Group 4C. Group 2D. Group 3Answer: Group 1