38. Explain why water forms into beads on a waxed car finish. __ 39. Hydrogen peroxide (H_(2)O_(2)) is a syrupy liquid with a relatively low vapor pressure and a normal boiling point of 152.2^circ C Rationalize the differences of these physical properties from those of water. 40. Carbon diselenide (CSe_(2)) is a liquid at room temperature . The normal boiling point is 125^circ C , and the melting point is -45.5^circ C Carbon disulfide (CS_(2)) is also a liquid at room temperature with normal boiling and melting points of 46.5^circ C and -111.6^circ C . re- spectively. How do the strengths of the intermolecular forces vary from CO_(2) to CS_(2) to CSe_(2) ? Explain.

38. Water forms into beads on a waxed car finish because the wax creates a hydrophobic (water-repelling) surface. This causes the water to minimize its contact with the surface and form droplets or beads.<br /><br />39. Hydrogen peroxide (H2O2) has a relatively low vapor pressure and a higher boiling point compared to water due to the presence of hydrogen bonding between its molecules. Hydrogen bonding is a stronger intermolecular force than the dipole-dipole interactions present in water, leading to a higher boiling point for hydrogen peroxide.<br /><br />40. The strengths of the intermolecular forces vary from CO2 to CS2 to CSe2 as follows:<br />- CO2: Weak van der Waals forces (London dispersion forces)<br />- CS2: Stronger van der Waals forces<br />- CSe2: Strongest van der Waals forces<br /><br />The increasing strength of the intermolecular forces is due to the increasing size and polarizability of the selenium atom in CSe2 compared to the sulfur atom in CS2 and the carbon atom in CO2.