Which of the following statements correctly describes a relationship between empirical formula and molecular formula? a) The empirical formula molar mass is greater than the molecular formula for all compounds.
b) The empirical formula and the molecular formula are the same for all compounds.
c) The empirical formula molar mass is less than or equal to the actual molar mass for all compounds.
d) The molecular formula is twice the empirical formula molar mass for all compounds.

the empirical formula will have less molar mass, or sometimes equal molar mass, when compared to the molecular formula

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.