Introduction:
In order to determine the number of paramagnetic species among Be2, B2, C2, and N2, we need to consider their electronic configurations and determine if they have any unpaired electrons.

Paramagnetic and Diamagnetic Species:
- Paramagnetic species: These are substances that have unpaired electrons and are attracted by a magnetic field.
- Diamagnetic species: These are substances that have all paired electrons and are not attracted by a magnetic field.

Electronic Configurations:
- Be2: Beryllium (Be) has an atomic number of 4, and its electronic configuration is 1s2 2s2. When two Be atoms come together to form Be2, they share their electrons and the molecular orbital diagram is formed. In this case, both the molecular orbitals are fully occupied, resulting in all paired electrons. Therefore, Be2 is diamagnetic.
- B2: Boron (B) has an atomic number of 5, and its electronic configuration is 1s2 2s2 2p1. When two B atoms come together to form B2, they share their electrons and the molecular orbital diagram is formed. In this case, there is one unpaired electron in the molecular orbitals. Therefore, B2 is paramagnetic.
- C2: Carbon (C) has an atomic number of 6, and its electronic configuration is 1s2 2s2 2p2. When two C atoms come together to form C2, they share their electrons and the molecular orbital diagram is formed. In this case, there are two unpaired electrons in the molecular orbitals. Therefore, C2 is paramagnetic.
- N2: Nitrogen (N) has an atomic number of 7, and its electronic configuration is 1s2 2s2 2p3. When two N atoms come together to form N2, they share their electrons and the molecular orbital diagram is formed. In this case, there are three unpaired electrons in the molecular orbitals. Therefore, N2 is paramagnetic.

Conclusion:
Out of the given species, B2, C2, and N2 are paramagnetic because they have unpaired electrons. Be2 is diamagnetic as it has all paired electrons. Hence, the number of paramagnetic species among Be2, B2, C2, and N2 is 1.