Final answer:
Nitrogen has the highest oxidation number of +4 in NO2 (nitrogen dioxide) among the provided options. So, the correct answer is B.
Step-by-step explanation:
The question asks which of the listed compounds contains nitrogen with the highest oxidation number. To determine oxidation numbers, we need to apply certain rules. For example, the oxidation number of nitrogen in NH3 (ammonia) is -3 because hydrogen generally has an oxidation number of +1. In NO2 (nitrogen dioxide), nitrogen typically has an oxidation number of +4. For N2, which is nitrogen gas, the oxidation number of nitrogen is 0 as it is in its elemental form. In NCl3 (nitrogen trichloride), nitrogen's oxidation number is +3 because chlorine generally has an oxidation number of -1. Lastly, in NO (nitric oxide), the oxidation number of nitrogen is +2.
Out of all these compounds, the highest oxidation number for nitrogen is in NO2, which is +4.
To support this further, in the compound N2O5 (dinitrogen pentoxide), which is not listed among the options provided but is useful for comparison, each nitrogen atom would have an oxidation number of +5 since oxygen is typically -2 and there are five of them to satisfy the overall neutral charge.