< b="" />Neutral Oxide of a Non-Metal< />

< b="" />Introduction< />
Oxides are compounds formed between oxygen and another element, which can be either a metal or a non-metal. Non-metal oxides have the tendency to be acidic or neutral in nature. In this case, we are looking for a neutral oxide of a non-metal.

< b="" />Explanation< />
To determine the neutrality of an oxide, we need to analyze its chemical formula and the oxidation numbers of the elements involved.

- < b="" />SO2< />: This is the chemical formula for sulfur dioxide. Sulfur has an oxidation number of +4, and oxygen has an oxidation number of -2. Therefore, the overall oxidation number of sulfur dioxide is zero. Since it is not equal to zero, SO2 is not neutral.
- < b="" />NO2< />: This is the chemical formula for nitrogen dioxide. Nitrogen has an oxidation number of +4, and oxygen has an oxidation number of -2. The overall oxidation number of nitrogen dioxide is also not zero, making it acidic rather than neutral.
- < b="" />P2O3< />: This is the chemical formula for diphosphorus trioxide. Phosphorus has an oxidation number of +3, and oxygen has an oxidation number of -2. The overall oxidation number of diphosphorus trioxide is zero, indicating its neutrality. However, P2O3 is a metal oxide, not a non-metal oxide, so it is not the correct answer.
- < b="" />CO< />: This is the chemical formula for carbon monoxide. Carbon has an oxidation number of +2, and oxygen has an oxidation number of -2. The overall oxidation number of carbon monoxide is zero, making it a neutral oxide of a non-metal.

Therefore, the correct answer is option 'D', CO.