In a chlorine molecule (Cl2), the atoms are held together by covalent bonds. However, when we talk about the intermolecular forces that act between these chlorine molecules, we primarily consider dispersion forces, also known as London dispersion forces.
These dispersion forces arise due to the temporary dipoles that occur when the electron distribution around the chlorine atoms shifts momentarily. While these forces are generally weak compared to other types of intermolecular forces, they are significant for nonpolar molecules like Cl2.
Now let’s look at the other options:
- Hydrogen bonding: This occurs only between molecules containing hydrogen bonded to highly electronegative atoms like nitrogen, oxygen, or fluorine. Chlorine does not exhibit hydrogen bonding.
- Ion dipole forces: These forces occur between ions and polar molecules, which is not applicable to Cl2 since it is neither ionic nor polar.
- Dipole-dipole forces: These occur between polar molecules. Cl2 is nonpolar and therefore does not have dipole-dipole interactions.
- None of the above: This is incorrect as dispersion forces are present.
In conclusion, the only significant force acting between chlorine molecules is dispersion forces. Therefore, the correct answer to the question is A: dispersion forces.