Which of the following factors contributes to the increase in atomic size within a group in the periodic table as the atomic number increases? a. more shielding of the electrons by the highest occupied energy level?
b. an increase in the size of the nucleus
c. an increase in the number of protons
d fewer electrons in the highest occupied energy level

A: more shielding of the electrons by the highest occupied energy level

Explanation:

The shielding effect describes the attraction between an electron and the nucleus in any atom with more than one electron shell. It is also referred to as the screening effect or atomic shielding. The increase in the number of occupied orbitals shields electrons in the highest occupied energy level from the attraction of protons in the nucleus.  The shielding effect is greater than the effect of the increase in nuclear charge, so the atomic size increases

fe 55.85 g/mol and h2o 18.02 g/mol.