Question

part a
how are the empirical formula and the molecular formula of a compound related?
the molecular formula is a whole - number multiple of the empirical formula.
the empirical formula is a whole - number multiple of the molecular formula.
the molecular formula shows only the relations between the elements in the compound, the empirical formula describes the total number
that are the same concepts.

Explanation:

The empirical formula gives the simplest whole - number ratio of atoms of each element in a compound. The molecular formula gives the actual number of atoms of each element in a molecule of the compound. If the empirical formula is \(EF\) and the molecular formula is \(MF\), then \(MF=(EF)_n\) where \(n\) is a positive integer (\(n = 1,2,3,\cdots\)). So the molecular formula is a whole - number multiple of the empirical formula.

The second option is wrong because it has the relationship reversed. The third option is incorrect as the empirical formula shows the simplest ratio (relations between elements in a simple sense) and the molecular formula shows the actual number. The fourth option is wrong as they are different concepts.

Answer:

The molecular formula is a whole - number multiple of the empirical formula.