Which type of forces primarily determine the state of matter and physical properties?

• A. Ionic bonds
• B. Covalent bonds
• C. Intermolecular forces
• D. Nuclear forces

Answer: (C)

Intermolecular forces are the main drivers of a substance’s state of matter and its physical properties. These are the attractions between separate molecules—such as hydrogen bonding, dipole-dipole interactions, and London dispersion forces—that determine how strongly molecules stick together. Their strength sets melting and boiling points, viscosity, surface tension, and vapor pressure. For example, hydrogen bonding in water makes it liquid at room temperature and gives it a relatively high boiling point, while the weak London forces in noble gases keep them as gases at the same temperature. In contrast, ionic and covalent bonds act within a molecule or a lattice, shaping chemical structure and bonding strength, but they don’t primarily establish the state of matter under ordinary conditions. Nuclear forces operate inside the nucleus and have no bearing on these macroscopic properties.