Thermal (Kinetic Theory, Heat Transfer, Thermal Properties)

A liquid is heated. Which of the following statements are incorrect?

• The liquid molecules expand.

• The intermolecular spacing increases.

• The molecules gain energy.

• The molecules move faster.

Which form of energy possessed by molecules is related to temperature?

• gravitational potential

• kinetic

• chemical potential

• nuclear

A heated surface loses heat by radiation. What does not affect the amount of heat lost per square metre of the surface?

• the area of the surface

• the colour of the surface

• the roughness of the surface

• the temperature of the surface

Blocks of gold are made by pouring hot, molten gold into moulds. The gold cools to its melting point and begins to solidify. As the gold solidifies, which statement is correct?

• Its temperature decreases and energy is lost from the gold to the surroundings.

• Its temperature decreases and no energy is lost from the gold to the surroundings.

• Its temperature stays constant and energy is lost from the gold to the surroundings.

• Its temperature stays constant and no energy is lost from the gold to the surroundings.

Which statement about solids, liquids and gases is correct?

• In a gas, particles move slowly downwards due to the force of gravity.

• In a liquid, particles move slowly in some directions only.

• In a solid, particles vibrate about fixed positions.

• Liquids and gases can be easily compressed

Boiling and evaporation are different processes. Which statement is not correct?

• Boiling occurs throughout the entire liquid but evaporation only occurs at the surface.

• Evaporation can only occur when the temperature of the liquid is high enough.

• Evaporation causes the temperature of a liquid to fall.

• When a boiling liquid is heated its temperature remains constant.

The rate of energy transfer from a body by radiation is affected by a number of factors. What does not affect the rate of transfer?

• colour of the surface

• surface area

• surface temperature

• the surrounding air pressure

Which statement is correct?

• The molecules in a gas are closer together than in a liquid.

• The molecules in a solid are much further apart than in a liquid.

• In a liquid, the kinetic energy of the molecules increases with increasing temperature.

• In a solid, the molecules can move around each other.

Which statement about the evaporation of a liquid is not correct?

• It changes the liquid into a gas.

• It cools the liquid.

• It occurs only at the boiling point of the liquid.

• It takes place at the surface of the liquid.

Water at the top of a hot water tank is heated and the water becomes hot. No water enters or leaves the tank. Which statement explains why water at the bottom of the tank stays cold for some time?

• Cold water at the top of the tank falls to the bottom.

• Hot water at the bottom of the tank rises to the top.

• The insulation is a poor conductor of heat.

• Water is a poor conductor of heat.