From each pair below (attached image), select the molecule that will display stronger intermolecular dipole-dipole forces in a sample of the pure substance.

(a) Consider a substance where the intermolecular forces hold the molecules in fixed rigid positions. What is the process called when enough heat has been added to the substance so that the molecules begin to flow? (b) Consider a substance where the intermolecular forces hold the molecules in close contact with each other, but the molecules can flow. What is the process called when enough heat has been added to the substance so that the molecules escape each other? (c) Consider a substance where the intermolecular forces hold the molecules in fixed rigid positions. What is the process called when enough heat has been added to the substance so that the molecules can escape each other?

- Suppose a small sample of pure X is held at  -236.°C and 2.0 atm. What will be the state of the sample (solid, liquid, or gas)? - Suppose the temperature is held constant at -236.°C but the pressure is decreased by 1.2 atm. What will happen to the sample (nothing, it will melt, it will freeze, it will boil, it will condense, it will sublime, or it will deposit)? - Suppose, on the other hand, the pressure is held constant at 2.0 atm but the temperature is increased by 137°C. What will happen to the sample (nothing, it will melt, it will freeze, it will boil, it will condense, it will sublime, or it will deposit)? All these are part of one question.