Unit 3 - Week 3 Revision

A sealed container of air is kept at a constant temperature. What will happen to the speed of the molecules of air in the container as time passes?

• The molecules will all reach the same speed.

• Some molecules will speed up and others will slow down, but the average speed will be constant.

• The molecules will slow down.

• There will be no change.

Which of the following statements about the kinetic theory of gases is NOT true:

• All molecules move with the same speed.

• Their average kinetic energy is directly proportional to the absolute temperature.

• All molecules make elastic collisions with each other and the walls of the container.

• The molecules travel in straight lines until they collide.

During an energy transfer process, 1000J of heat is removed from a gas while 100J of work is done by the gas. What is the change in internal energy of the gas?

• +1100J

• +900J

• -900J

• -1100J

Convection can NOT occur in which of the following substances?

• Water

• Ice

• Steam

• Water Vapour

How much heat energy is needed to raise the temperature of 2kg of water from 5 °C to 100 °C? The specific heat capacity of water is 4180 J/kg °C.

• 42000 J
• 840000 J
• 798000 J

If I have 2 blocks of Aluminium (one of 1kg and one of 10 kg) and heat them up. Which one heats up the fastest?

• 1 kg
• 10 kg
• They both heat up at the same speed
• They don't heat up.

A lead ball (c = 128J/kgK) with mass 75.0g and a temperature of 25°C is placed on a small cube of ice at 0°C, which then melts. If 75.0g of water (c = 4180J/kgK) at 25°C is poured onto a cube of ice, which of the following is true?

• The water would melt more ice than the lead ball.

• The water would melt less ice than the lead ball.

• The water would melt the same amount of ice as the lead ball.

• Neither the water nor lead ball would melt any ice.

Which two words completes the definition of specific heat capacity: The amount of thermal energy transfer necessary to raise the ______ of one ______ of a substance by one degree.

• Temperature, Kilogram

• Temperature, Gram

• Heat, Kilogram

• Heat, Gram