Which of the following statements is false? 

a) The electron affinity of phosphorus is less exothermic than those of both silicon and sulfur. 

b) The second ionization energy of oxygen is less than the first ionization of fluorine.

c) As the principal quantum number of an atom increases the effective nuclear charge will increase. 

d) Cations are smaller than their parent atoms. 

e) The second electron affinity of an atom will be more exothermic than the first electron affinity.