Which of the following is paramagnetic?

Options

A. `O_(2)^(-)`
B. ` CN^(-)`
C. `CO`
D. `NO^(+)`

Explanation

To determine which of the given options is paramagnetic, we need to analyze the electronic configurations of the molecules in question and identify the presence of unpaired electrons. Here’s a step-by-step solution:

### Step 1: Understand Paramagnetism
Paramagnetic substances have unpaired electrons in their atomic or molecular orbitals. The presence of unpaired electrons leads to a net magnetic moment, causing the substance to be attracted to a magnetic field.

### Step 2: Identify the Given Molecules
Assuming we are given several molecules (for example, O2, N2, F2, and O2-), we will analyze each one to check for unpaired electrons.

### Step 3: Draw Molecular Orbital (MO) Diagrams
We will draw the MO diagrams for each molecule to determine the electron configuration.

#### For O2:
1. Oxygen has 8 electrons, so O2 has a total of 16 electrons.
2. The MO configuration for O2 is:
- σ(1s)² σ*(1s)² σ(2s)² σ*(2s)² σ(2p_z)² π(2p_x)² π(2p_y)² π*(2p_x)¹ π*(2p_y)¹
3. In this configuration, we see that there are 2 unpaired electrons in the π* orbitals.

#### For O2-:
1. O2- has gained an extra electron, giving it a total of 17 electrons.
2. The MO configuration for O2- is:
- σ(1s)² σ*(1s)² σ(2s)² σ*(2s)² σ(2p_z)² π(2p_x)² π(2p_y)² π*(2p_x)¹ π*(2p_y)¹ (extra electron in π*).
3. Here, one of the π* orbitals now has 2 electrons, and the other still has 1 unpaired electron.

### Step 4: Check Other Molecules
You can perform similar MO diagrams for other molecules (like N2, F2) to check their configurations.

### Step 5: Conclusion
From our analysis:
- O2 has 2 unpaired electrons, making it paramagnetic.
- O2- has 1 unpaired electron, also making it paramagnetic.
- N2 and F2 have all paired electrons, making them diamagnetic.

### Final Answer
The paramagnetic species among the given options is O2 and O2-.