10 Multigle Choice 3 point In which of the following oai s of chemical formalas do both for mulas represent compounds? HCN and \( \mathrm{N}_{2} \) \( \mathrm{CO}_{2} \) and \( \mathrm{O}_{2} \) \( \mathrm{O}_{2} \) and \( \mathrm{O}_{3} \) \( \mathrm{N}_{2} \mathrm{O}_{4} \) and \( \mathrm{NO}_{2} \) Multiple Choice 1 point

The correct answer is: **\( \mathrm{N}_{2}\mathrm{O}_{4} \) and \( \mathrm{NO}_{2} \)** **Explanation:** - **HCN and \( \mathrm{N}_{2} \):** - **HCN** (Hydrogen Cyanide) is a compound composed of hydrogen, carbon, and nitrogen. - **\( \mathrm{N}_{2} \)** (Nitrogen gas) is an elemental molecule, not a compound. - **\( \mathrm{CO}_{2} \) and \( \mathrm{O}_{2} \):** - **\( \mathrm{CO}_{2} \)** (Carbon Dioxide) is a compound composed of carbon and oxygen. - **\( \mathrm{O}_{2} \)** (Oxygen gas) is an elemental molecule, not a compound. - **\( \mathrm{O}_{2} \) and \( \mathrm{O}_{3} \):** - Both **\( \mathrm{O}_{2} \)** (Oxygen gas) and **\( \mathrm{O}_{3} \)** (Ozone) consist solely of oxygen atoms. They are different allotropes of oxygen, not compounds. - **\( \mathrm{N}_{2}\mathrm{O}_{4} \) and \( \mathrm{NO}_{2} \):** - **\( \mathrm{N}_{2}\mathrm{O}_{4} \)** (Dinitrogen Tetroxide) and **\( \mathrm{NO}_{2} \)** (Nitrogen Dioxide) are both compounds composed of nitrogen and oxygen. Therefore, both formulas in the fourth option represent chemical compounds. **Answer:** Both \( \mathrm{N}_{2}\mathrm{O}_{4} \) and \( \mathrm{NO}_{2} \) are compounds.