Question

The eighteenth element in the periodic table resembles with the -

• A. First element
• B. Second element
• C. Fourth element
• D. Ninth element

Answer 1

Answer: (B)

Each period consists of a series of elements whose atoms have the same principal quantum number $(n)$ of the outermost shell, $ie$ , in second period, $n=2$ , this shell has four orbitals (one $2s$ and three $2p$ ) which can have eight electrons, hence second period contain 8 elements from atomic number 3 to 10.