Question

Assuming that the number of maximum permissible shells is 5, elements would be there in the periodic table is:

• A. 52
• B. 54
• C. 55
• D. 51

Answer 1

The correct option is B 54

According to Aufbau principle the order of filling of orbitals is:
$1s2s2p3s3p4s3d4p5s4d5p6s4f5d6p$
For maximum shell of 5, electrons will be filled upto 5p orbital as (each period)
$\left(1s^2\right)\left(2s^{2}2p^6\right)\left(3s^{2}3p^6\right)\left(4s^{2}3d^{10}4p^6\right)\left(5s^{2}4d^{10}5p^6\right)$
$2+8+8+18+18=54$
Therefore maximum number of atoms would be 54.
option B is correct.