Which of the following has the lowest boiling point? (Punjab PMET 2008)

2 CuCl has the lowest boiling point among the given options. Sodium and Caesium chlorides are solids with high melting and boiling points because of the large amount of heat which is needed to break the strong ionic attractions.The rests are liquids or low melting point solids. The attractions in the others will be much weaker intermolecular forces such as Van der Waals dispersion forces. These vary depending on the size and shape of the molecule, but will always be far weaker than ionic bonds.