Thermal Properties of Matter

A block of ice is heated until it has melted. The water produced is heated until it boils. Which choice is correct?

• A

• B

• C

• D

When a liquid evaporates, some molecules escape from it and its temperature changes. Where do the molecules escape from and what is the effect of evaporation on the liquid temperature?

• A

• B

• C

• D

A heater supplies 80 J of energy to a block of metal. The temperature of the metal increases by 20 degC. What happens to the internal energy of the same block when its temperature falls by 10 degC?

• decrease by 40 J

• decrease by 160 J

• increase by 40 J

• increase by 160 J

A hot drink is left in a room which has a temperature of 20 degC. What happens to the drink in 10 minutes?

• density becomes lower

• internal energy becomes lower

• particles move more quickly

• energy of particles become equal

Ice at 0 degC is placed in warm water. The ice melts. As ice melts, which statement is correct?

• internal energy of ice decreases

• internal energy of water decreases

• temperature of ice increases

• temperature of water increases

A sample of liquid at a temperature of 80 degC cools down and solidifies. The graph shows the temperature against time as the sample cools. How long does the process of solidification take?

• 2 min

• 3 min

• 4 min

• 5 min

Some statements about boiling and evaporation are below. Which is incorrect?

• Boiling occurs at the liquid surface.

• Boiling forms bubbles as liquid turns to gas.

• Evaporation occurs at any temperature.

• Rate of evaporation is affected by exposed surface area of the liquid.

The bar graph shows the temperature at which some substances change state.

Which substance freezes at 800 degC?

• carbon dioxide

• ethanol

• sodium chloride

• water

When rubbed with ethanol the hand feels cold because ...

• the temperature of the ethanol is lower than the body temperature

• ethanol on the skin prevents the loss of heat from the body

• thermal energy is transferred from ethanol to the body

• heat is removed from the body as ethanol evaporates

Blocks of gold are made by pouring hot, melted gold into moulds. The gold cools to its melting point and begins to solidify.  As it solidifies, its temperature ............................

• stays constant and energy is lost from the gold

• stays constant and no energy is lost from the gold

• decreases and energy is lost from the gold

• decreases and no energy is lost from the gold.