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The set of compounds that have the same empirical formula is b) N₂O₄ and NO₂.
The Empirical Formula is the most simple representation of the atom ratio in a chemical compound. Of the listed sets of compounds, the only in which the atom ratio is the same for both compounds is the pair N₂O₄ and NO₂ in which the atom ratio N:O is 1:2. The Empirical Formula for this pair is NO₂.
N₂O₄ has the same atom ratio as NO₂ but this formula has each atom multiplied by two. However, its Empirical Formula is the same.
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