Question

A, B, C are three elements with atomic numbers, Z-1, Z and Z+1 respectively. B is an inert gas. Identify the elements having same valence shell.

• A. A, B
• B. B, C
• C. A, C
• D. A, B, C

Answer 1

The correct option is A A, B

The element having atomic number one greater than inert gases in alkali metal of next period and one less than inert gases is halogen of the same period. Thus, for given conditions A and B belong to the same period.