Determine whether each statement regarding penetration and shielding is true or false. (Assume that all lower energy orbitals are fully occupied.)

a. An electron in a 3s orbital is more shielded than an electron in a 2s orbital.

b. An electron in a 3s orbital penetrates into the region occupied by core electrons more than electrons in a 3p orbital penetrates into the region occupied by core electrons.

c. An electron in an orbital that penetrates closer to the nucleus always experiences more shielding than an electron in an orbital that does not penetrate as far.

d. An electron in an orbital that penetrates close to the nucleus tends to experience a higher effective nuclear charge than an electron in an orbital that does not penetrate close to the nucleus.