Question

why does ice change to water as energy is added at the melting point?
a. kinetic energy is removed from the molecules so they separate.
b. molecular motion decreases until the temperature begins to increase.
c. molecules vibrate quicker, and their motion overcomes the forces of attraction.
d. all of the forces of attraction between molecules disappear at the melting point.
o a
o b
o c
o d

Explanation:

When energy is added to ice at its melting - point, the heat energy is used to increase the kinetic energy of the water molecules. As a result, the molecules vibrate more quickly. The increased molecular motion overcomes the intermolecular forces of attraction that hold the molecules in a fixed, ordered arrangement in the solid (ice) state, allowing the ice to change into the liquid (water) state. Option a is incorrect because kinetic energy is added, not removed. Option b is incorrect as molecular motion increases at the melting - point. Option d is incorrect because not all forces of attraction disappear at the melting - point; they are just weakened.

Answer:

C. Molecules vibrate quicker, and their motion overcomes the forces of attraction.