If 2s-2p mixing is not operative then the no. of diamagnetic species among the following isBe2, B2, N2, C2, F2 4 5 3 2

To determine the number of diamagnetic species among Be2, B2, N2, C2, F2, we need to understand the concept of diamagnetism.

Diamagnetic substances are those that do not have any unpaired electrons and are not attracted to a magnetic field. They are repelled by a magnetic field.

Now, let's examine each molecule:

1. Be2: Beryllium (Be) has 4 electrons. In the Be2 molecule, all 4 electrons from each Be atom are paired. So, Be2 is diamagnetic.

2. B2: Boron (B) has 5 electrons. In the B2 molecule, there are 10 electrons, 8 of which are paired and 2 are unpaired. So, B2 is not diamagnetic.

3. N2: Nitrogen (N) has 7 electrons. In the N2 molecule, all 14 electrons are paired. So, N2 is diamagnetic.

4. C2: Carbon (C) has 6 electrons. In the C2 molecule, there are 12 electrons, 10 of which are paired and 2 are unpaired. So, C2 is not diamagnetic.

5. F2: Fluorine (F) has 9 electrons. In the F2 molecule, all 18 electrons are paired. So, F2 is diamagnetic.

So, the number of diamagnetic species among Be2, B2, N2, C2, F2 is 3 (Be2, N2, F2).