Which of the following oxide does not form dimer?

Options

A. `NO`
B. `ClO_(2)`
C. `NO_(2)`
D. All of these

Answer

To determine which of the following oxides does not form a dimer, we will analyze the given oxides one by one.

### Step 1: Analyze Nitric Oxide (NO)
- **Structure**: Nitric oxide has the structure of nitrogen (N) double bonded to oxygen (O), with one unpaired electron on nitrogen.
- **Bonding**: The bond order of NO is 2.5 due to the presence of a double bond and one unpaired electron.
- **Dimerization**: Due to the presence of an unpaired electron, NO can form dimers, but it does not do so readily because the bond order remains the same (2.5) and does not favor dimerization.

### Step 2: Analyze Chlorine Dioxide (ClO2)
- **Structure**: Chlorine dioxide has the structure of Cl double bonded to two oxygen atoms, with one of the oxygen atoms having a double bond and the other having a single bond, resulting in an odd electron.
- **Bonding**: The presence of an odd electron makes it less likely to form stable dimers.
- **Dimerization**: ClO2 does not readily form dimers due to its odd electron configuration.

### Step 3: Analyze Nitrogen Dioxide (NO2)
- **Structure**: Nitrogen dioxide has the structure of nitrogen double bonded to one oxygen and single bonded to another oxygen, with a coordinate bond.
- **Bonding**: The presence of a coordinate bond and the hybridization of electrons allow for a more stable configuration.
- **Dimerization**: NO2 readily forms dimers and can be converted to dinitrogen tetroxide (N2O4) due to its ability to stabilize through dimerization.

### Conclusion
From the analysis:
- **NO** and **ClO2** do not form dimers readily.
- **NO2** does form dimers.

Thus, the oxides that do not form dimers are **NO** and **ClO2**.