Ethylene glycol (HOCH₂CH₂OH) is the major component of antifreeze. It is a slightly viscous liquid, not very volatile at room temperature, with a boiling point of 198°C. Pentane (C₅H₁₂), which has about the same molecular weight, is a nonviscous liquid that is highly volatile at room temperature and whose boiling point is 36.1°C. Explain the differences in the physical properties of the two substances.