Which pair of species are referred to as suboxides respectively?

Options

A. `CO,NO`
B. `SO_(2),CaO`
C. `N_(2)O`,`CO`
D. `N_(2)O,C_(3)O_(2)`

Explanation

To determine which pair of species are referred to as suboxides, we need to understand the definition of suboxides and analyze the given options.

### Step-by-Step Solution:

1. **Understanding Suboxides**:
- Suboxides are defined as oxides in which the electropositive element (the metal or non-metal that is less electronegative) is present in a greater proportion than in normal oxides. This means that the ratio of the electropositive element to oxygen is higher than what is typically found in standard oxides.

2. **Analyzing the Options**:
- The question provides four species: CO (carbon monoxide), NO (nitric oxide), SO2 (sulfur dioxide), and PAO (which seems to be a typo, possibly referring to a different oxide).
- We need to identify pairs that fit the criteria of suboxides.

3. **Identifying Suboxides**:
- Let's examine the relevant species:
- **N2O (Dinitrogen monoxide)**: This compound has a lower proportion of oxygen compared to nitrogen, making it a suboxide.
- **C3O2 (Tricarbon dioxide)**: This compound also has a lower proportion of oxygen compared to carbon, thus it qualifies as a suboxide as well.

4. **Conclusion**:
- From the analysis, the pair of species that are referred to as suboxides are **N2O and C3O2**. Therefore, the correct answer is option D.

### Final Answer:
The pair of species referred to as suboxides are **N2O and C3O2**.