Question

What must happen for water to boil at a given pressure?

O A. The water molecules must become more orderly.
O B. The water must gain thermal energy from its surroundings.
O C. The average kinetic energy of the water molecules must decrease.
D. The water must give off thermal energy to its surroundings.

Answer 1

The water must give off thermal energy to its surroundings.

Answer 2

B. The water must gain thermal energy from its surroundings.

Step-by-step explanation:

Boiling is the process whereby a substance is changed from a liquid state to a gaseous state due to the application of heat. For boiling to be achieved, a liquid substance must reach or exceed its boiling point, which is the specific temperature at which a specific liquid boils.

For this change of state i.e. from liquid to gas, to occur, atoms or molecules of the liquid must gain kinetic energy and move faster. However, this kinetic energy cannot be attained without a rise in temperature, which causes the molecules to gain THERMAL ENERGY or heat energy and move fast. Thermal energy is the energy that arises from a hot substance.

Therefore, for water to boil at a given pressure, it must gain thermal energy from its external surroundings, which causes its molecules to have an increased kinetic energy and move faster. This fast movement of the molecules causes the transition of phases (from liquid to gas).