Question

which statement best explains why water has a higher boiling point than ethane?
ethane molecules are smaller than water and can move faster.
water molecules need relatively less heat energy to move.
water molecules form hydrogen bonds, which cannot be broken by heating water.
ethane molecules have no hydrogen bonds and need less energy to separate.

Explanation:

Hydrogen bonds are strong intermolecular forces. Water has hydrogen - bonding due to the electronegative oxygen and hydrogen atoms, while ethane has only weak van der Waals forces. More energy is needed to break the intermolecular forces in water, resulting in a higher boiling point. Heating water does break hydrogen bonds. Smaller size or faster - moving molecules don't directly explain the boiling - point difference. Water molecules need more heat energy to move compared to ethane in terms of boiling.

Answer:

D. Ethane molecules have no hydrogen bonds and need less energy to separate.