Which formula is an empirical formula?

(1) N2O4

(2) NH3

(3) C3H6 (4) P4O10

Answer and Explanation:

An empirical formula is a chemical formula that has simplest whole number ratios on atoms. Therefore if we look at the subscript numbers in an empirical formula, we should not be able to divide them anymore. Let's look at each answer choice and determine whether it is an empirical formula or not. 1. N2O4 ( The subscripts are 2 and 4, these are not simplest ratio numbers since we can divide both numbers by 2, and get 1 and 2). 2. NH3 (The subscripts are 1 and 3. These are indeed simplest ratio subscripts since we can not divide them anymore.) Therefore choice 2 is the correct answer.

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