Final answer:
A gas would likely have the weakest intermolecular forces compared to a liquid or crystalline solid, given the free movement of particles within gases and their ability to fill a container.
Step-by-step explanation:
Among gas, liquid, and crystalline solid, a gas would likely have the weakest intermolecular forces. Solids are characterized by their strong intermolecular forces that hold the particles in place, giving them a definite shape and volume. Liquids have intermolecular forces that are strong enough to keep the molecules relatively close but not so strong as to keep them rigidly in place, therefore liquids have a definite volume but no definite shape. Gases have the weakest intermolecular forces, allowing their particles to move freely and fill the container they are in. Therefore, the answer to the question is A. Gas.
If a substance has relatively strong intermolecular forces, a high melting point, and is not easily compressed, this substance would most likely be a solid. The intermolecular forces within solids are greater than those in liquids and gases, allowing them to maintain a fixed volume and shape.
In summary, molecular crystals have more considerable intermolecular forces than gases, but they are still weaker than ionic or covalent bonds. Intermolecular forces are responsible for the physical states of matter and influence their melting and boiling points.