Which of the following statements is true?
a) non metals generally have higher ionization energies than metals
b) the first ionization energy is always higher than the second
c) the alkali metals have the highest ionization energies of all elements
d) the electrons further from the nucleus are the most difficult to remove

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.