Which of the following statements are true for many-electron atoms? If false, explain why.

(a) The effective nuclear charge Z_effe is independent of the number of electrons present in an atom.

(b) Electrons in an s-orbital are more effective than those in other orbitals at shielding other electrons from the nuclear charge because an electron in an s -orbital can penetrate to the nucleus of the atom.

(c) Electrons having l = 2 are better at shielding than electrons having l = 1.

(d) Z_effe for an electron in a p-orbital is lower than for an electron in an s -orbital in the same shell.