Answer:
C. N2O5.
Step-by-step explanation:
Let's remember the concept of the empirical formula: empirical formulas show the simplest ratio of whole numbers of atoms in a substance.
Let's analyze each option:
A. N2O4 doesn't have the simplest ratio in the number of atoms because we can 'simplify it' if we divide each number by 2, so we would have NO2. It's not an empirical formula.
B. N2H6 can be 'simplify it' too if we divide each number of atoms by 2, so we will obtain NH3. It's not an empirical formula.
C. N2O5 cannot be 'simplify it' because there are no numbers divisible by 2 and 5; in fact, they are prime numbers, so based on the logic of the given definition of empirical formula, this could be an empirical formula.
The answer would be C. N2O5.