Final answer:
The empirical formula for the molecular formula B2Cl4 is obtained by dividing the subscripts by their greatest common divisor, resulting in BCl2.
Step-by-step explanation:
The empirical formula of a compound represents the simplest whole number ratio of the elements in the compound. To determine the empirical formula for the molecular formula B2Cl4, we divide the subscripts by their greatest common divisor, if any. In this case, both subscripts, 2 for boron (B) and 4 for chlorine (Cl), can be divided by 2.
Dividing the subscript of boron by 2 gives us 1, and dividing the subscript of chlorine by 2 gives us 2. Hence, the empirical formula is reduced to BCl2.