ANS:A - are held together by stronger inter-molecular forces.

Gases diffuse faster compared to liquids primarily because gas molecules move faster due to their higher kinetic energy. This is attributed to the fact that gas molecules have more space between them and experience weaker intermolecular forces compared to liquid molecules. In a gas, molecules are spaced farther apart and move freely in all directions at high speeds. This allows gas molecules to spread out more rapidly and diffuse through a medium. On the other hand, in a liquid, molecules are held closer together by stronger intermolecular forces, resulting in slower movement and diffusion compared to gases. Therefore, the correct reason is that gas molecules move faster compared to liquid molecules, leading to faster diffusion of gases. Certainly! Intermolecular forces are the attractive forces that exist between molecules. These forces play a significant role in determining the physical properties of substances, including their state of matter (solid, liquid, or gas), boiling and melting points, and their ability to diffuse. In liquids, molecules are held together by stronger intermolecular forces compared to gases. These intermolecular forces include:

1. Van der Waals forces: These are weak attractive forces that exist between all molecules, regardless of their polarity. Van der Waals forces include dispersion forces (also known as London forces), dipole-dipole interactions, and hydrogen bonding.
2. Hydrogen bonding: This is a type of dipole-dipole interaction that occurs between a hydrogen atom bonded to an electronegative atom (such as oxygen, nitrogen, or fluorine) and another electronegative atom in a nearby molecule. Hydrogen bonding is stronger than other types of intermolecular forces and contributes significantly to the properties of substances like water.
3. Dipole-dipole interactions: These occur between polar molecules, where the positive end of one molecule is attracted to the negative end of another molecule. Dipole-dipole interactions are weaker than hydrogen bonding but stronger than dispersion forces.

In liquids, the molecules are close together and experience these intermolecular forces, which hold them in relatively fixed positions but still allow them to move past each other, resulting in the fluidity characteristic of liquids. In gases, however, the intermolecular forces are much weaker. Gas molecules are separated by large distances compared to liquid molecules and experience minimal attraction to each other. As a result, gas molecules move freely and rapidly in random directions, with high kinetic energy, leading to rapid diffusion. Therefore, the statement "are held together by stronger intermolecular forces" refers to the fact that in liquids, the intermolecular forces are stronger compared to gases, which contributes to the slower diffusion observed in liquids compared to gases.