Question

Which formula is both a molecular and an empirical formula?

Answer 1

3 C3H8O
because you cannot divide the subscripts anymore. The molecular formula is in it's simplest form. And C3H8O is a molecule as well. 

Answer 2

Answer : The correct option is, (3) $C_3H_8O$

Explanation :

Empirical formula : It is defined as the simplest or most reduced ratio of atoms in a compound.

Molecular formula : It is defined as the how many atoms of each element present in a compound.

From the given options, the option (3) $C_3H_8O$ formula represent both a molecular and an empirical formula.

From $C_3H_8O$ formula, we can determine the molecular formula by multiplying the whole numbers (1, 2, 3, 4 ....etc.)

While the other options, (1), (2) and (4) do not represent both a molecular and an empirical formula. Only represent the molecular formula.

The molecular formula of Glucose is, $C_6H_{12}O_6$ and the empirical formula will be, $C_1H_2O_1$

The molecular formula of Ethanoic acid is, $C_2H_4O_2$ and the empirical formula will be, $C_1H_2O_1$

The molecular formula of Butene is, $C_4H_8$ and the empirical formula will be, $C_1H_2$

Hence, the formula represent both a molecular and an empirical formula is, $C_3H_8O$