In which of the following compounds does nitrogen have an oxidation number of -3?

• A. N2O
• B. NH3
• C. NO2
• D. HNO3

Answer: (B)

Verified step by step guidance

1. Recall the general rules for assigning oxidation numbers: the sum of oxidation numbers in a neutral compound is zero, and common oxidation states for hydrogen and oxygen are +1 and -2, respectively.
2. For each compound, assign oxidation numbers to known elements and use the overall charge balance to find nitrogen's oxidation number.
3. In \(\mathrm{N_2O}\), oxygen is usually -2, so set up the equation: \$2x + (-2) = 0\(, where \)x\( is the oxidation number of nitrogen. Solve for \)x$.
4. In \(\mathrm{NH_3}\), hydrogen is +1, so set up the equation: \(x + 3(+1) = 0\), where \(x\) is nitrogen's oxidation number. Solve for \(x\).
5. Repeat the process for \(\mathrm{NO_2}\) and \(\mathrm{HNO_3}\), then compare the nitrogen oxidation numbers to identify which compound has nitrogen at -3.