Heating a substance increases its thermal energy, which translates to an increase in the average kinetic energy of its particles. For a liquid, this means the molecules move, vibrate, and rotate more rapidly and collide with each other more frequently and with more energy. The strength of the intermolecular forces is an intrinsic property of the substance and does not change, but the increased kinetic energy makes it easier for particles to overcome these forces. Significant expansion (A) and bond breaking (D) do not occur with gentle heating within a single phase.

Sublimation is a phase change from solid to gas. In the solid phase, $$CO_2$$ molecules are held by intermolecular forces in a fixed crystal lattice, where they can only vibrate. In the gas phase, these forces have been overcome, and the molecules are far apart, moving randomly and rapidly. Phase changes overcome intermolecular forces, not the strong intramolecular covalent bonds.

The high compressibility of gases is a direct result of the large amount of empty space between particles. When pressure is applied, this empty space is reduced, and the particles are forced closer together. In liquids and solids, particles are already in close contact, so there is very little empty space to reduce. While the negligible forces (Choice A) contribute to gas behavior, the large intermolecular distance is the direct structural reason for compressibility.

During melting (fusion), a substance goes from a closely packed solid to a closely packed liquid. The change in volume ($$ΔV_{fus}$$) is therefore relatively small (typically a small positive value for most substances). During boiling (vaporization), the substance goes from a closely packed liquid to a gas where particles are very far apart. This results in a very large increase in volume ($$ΔV_{vap}$$). Therefore, $$ΔV_{vap}$$ is much greater than $$ΔV_{fus}$$

This statement is incorrect because particles in the liquid phase have NOT completely overcome interparticle forces. These forces are still significant and are responsible for holding the particles in close contact, giving liquids a definite volume. The particles have enough kinetic energy to move past one another (flow), but not enough to escape the bulk of the liquid as in the gas phase. The other statements are correct descriptions.

Dynamic equilibrium means that opposing processes are occurring at equal rates, resulting in no net macroscopic change. In liquid-vapor equilibrium, particles are constantly moving from the liquid to the gas phase (evaporation) and from the gas to the liquid phase (condensation). At equilibrium, the rate of evaporation equals the rate of condensation. This is a dynamic process, not a static one where movement ceases.

This question tests comparing particle motion in solids and liquids at the same temperature. Both have kinetic energy, but liquids allow particles to change neighbors due to higher mobility, while solids restrict to vibration in place. This difference arises from slightly higher kinetic energy relative to attractions in liquids. Choice A is most accurate. A tempting distractor is choice B, stating solids have no kinetic energy, from the misconception of equating macroscopic stillness with zero microscopic motion, ignoring vibrational energy. When comparing phases, note that temperature equates average kinetic energy, but phase determines motion type based on force balance.

This question tests inferring phases from particle diagrams at the same temperature. Sample 1's ordered array suggests solid with vibrational motion, while Sample 2's close but disordered particles indicate liquid with sliding motion. Same temperature implies similar kinetic energy, but phase depends on attraction strength relative to energy. Choice A is supported. A tempting distractor is choice D, claiming both solids due to closeness, based on the misconception that density alone determines solidity, ignoring order's role. When comparing samples, use arrangement patterns to differentiate solids from liquids beyond mere proximity.

This question tests predicting gas behavior upon barrier removal in a container. Gas particles, being far apart and moving freely, will diffuse to occupy both halves due to random motion and lack of strong attractions. This reflects the gaseous property of expanding to fill available volume. Choice A predicts correctly. A tempting distractor is choice B, suggesting gases have definite volume, from the misconception of confusing gas with liquid properties, whereas gases lack definite volume. For diffusion scenarios, remember gases maximize entropy by spreading out unless confined.

This question tests understanding of relative particle spacing across phases. The correct order from smallest to largest spacing is solid < liquid < gas (S < L < G), reflecting the decreasing influence of intermolecular forces relative to kinetic energy. In solids, particles are packed closely in ordered arrangements; in liquids, particles remain in contact but with slightly more space due to less ordered packing; in gases, particles are separated by large distances relative to their size. The spacing differences explain density variations: gases are about 1000 times less dense than liquids or solids, while liquids are typically only slightly less dense than solids. Choice A (G < L < S) is incorrect because it reverses the order—this misconception might arise from confusing particle speed with spacing. Remember that particle spacing increases dramatically from solid to liquid to gas, with the liquid-to-gas transition showing the largest change.