Final answer:
Viscosity is influenced by molecular shape, size, and intermolecular forces, and increases with stronger intermolecular forces and longer molecular chains. High temperatures can decrease viscosity by increasing the kinetic energy of molecules, helping to overcome cohesive forces.
Step-by-step explanation:
How Viscosity Depends on Molecular Shape and Size
Viscosity is a measure of a fluid's resistance to flow and is influenced by the molecular shape, size, and intermolecular forces (IMFs) of the fluid's molecules. Liquids that have long, flexible molecules tend to have higher viscosities because these molecules can become entangled with each other, making it more difficult for the liquid to flow. In addition, intermolecular forces like London dispersion forces tend to increase with the length of the molecules' chains, further contributing to higher viscosity.
When considering molecular features that make liquids highly viscous, option (b) viscosity increases with stronger intermolecular forces is correct. Liquids with more structurally complex molecules and stronger IMFs have higher viscosities. As the temperature increases, the kinetic energy of the molecules increases, allowing them to overcome these cohesive forces more easily, which consequently decreases the viscosity of the liquid.