What will be the atomic number of an element X which is placed in period 2 and group17?

Correct option is D

The correct answer is (d) 9.
· The atomic number of an element X placed in period 2 and group 17 would be 9.
· The elements in periodic table are placed in periods and groups. Periods are horizontal rows that has increasing atomic numbers. Groups are vertical columns. There are 7 periods and 18 groups in periodic table.
· Period number refers to the number of electron shells in an atom. So, period 2 means element X has 2 electron shells.
· Group number represents the number of valence electrons in an atom. Therefore, group 17 signifies that element X has 7 valence electrons.
· Atomic number indicates the number of protons in an atom's nucleus. Since the number of protons and electrons is equal in a neutral atom, the atomic number is also equal to the number of protons.