The solid is not absorbing any heat C-The molecules are moving faster.

D-The molecules are further apart.

2- Ice is taken from a freezer and left in a room. The ice melts and eventually the water reaches room temperature. Which energy transfers take place?

energy transfer

during melting energy transfer after melting A from ice to room from water to room B from ice to room from room to water C from room to ice from room to water D from room to ice from water to room ???? / [May-2008]

3- A student is investigating the evaporation of water. The student can change:

-the depth of the water; -the surface area of the water; -the temperature of the water.

How many of these changes, if any, would alter the rate at which evaporation occurs? A 0 B 1 C 2 D 3 [May-2008]

4- A liquid evaporates rapidly. Why does it cool?

A - Air molecules remove heat by contact with the liquid surface. B - Energy is lost by convection currents. C - Fewer molecules are left in the liquid. D - Some of the most energetic molecules leave the liquid. [Nov-2002] / [Nov-2010]

5- A swimmer climbs out of a swimming pool on a warm, dry day. Almost immediately he begins to feel cold. Why is this?

A The water allows a convection current to remove heat from his skin. B The water takes latent heat from his body in order to evaporate. C The water on his skin is a good conductor of heat.

D The water prevents infra-red radiation from reaching his body. [May-2003] 6- A substance that is originally a solid is heated strongly for some time.

At one stage, the energy given to the substance is used as latent heat of vaporisation. At this stage, what change does the energy cause?

A It breaks the bonds holding the molecules together. Molecules escape from the liquid. B It breaks the bonds holding the molecules together. The solid becomes liquid.

C It makes the molecules move faster but there is still a strong attraction between them. D It makes the molecules move faster and so the temperature rises.

7- Which factors increase the rate of evaporation of a liquid?

increasing temperature increasing surface area increasing depth

A yes yes yes

B yes yes no

C yes no yes

D no yes yes

[May-2005] / [Nov-2008]

8- Some of the more energetic molecules in a liquid leave the surface, leaving the rest of the liquid slightly cooler. What is the name given to this process?

A – boiling B – condensation C – evaporation D – freezing [May-2006] 9- A substance consists of particles that are close together and moving past each other at random. The average speed of the particles is gradually increasing. What best describes the substance?

A - a liquid being boiled to form a gas B - a liquid being heated C - a solid being heated D - a solid being melted to form a liquid

10- A substance is heated in an enclosed space until it becomes a gas. After the heater is removed, the

temperature is recorded at regular intervals. The graph shows cooling of the substance.

What does the section PQ represent?

A - boiling B – condensing C - melting D – solidifying [Nov-2002]

11- Ice at –10 °C is heated at a constant rate until it is water at +10 ° C. Which graph shows how the temperature changes with time? B

12- When a liquid changes into a gas at a constant temperature, the temperature is known as its A- absolute zero B-boiling point C-evaporation point D-dew point

13- Given that the specific latent heat of vaporization of oxygen is 214 kJ kg-1, how much heat will be

absorbed when 3 kg of oxygen is boiled off at its boiling point? A- 64 kJ B- 140 kJ C- 14 kJ D- 642 kJ

14- When ice melts to become water, which force must be overcome? A the attraction between electrons and the nucleus

B the attraction between the atoms in a molecule C the force between molecules

D the force of gravity [Nov-2002] / [Nov-2008]

15-

The diagram shows a cross-section through a rain-water puddle formed in a shallow hole in a road surface.

Over a period of time, air temperature, wind speed and wind direction remain constant. What happens to the rate of evaporation of water from the puddle?

A It decreases, because the surface area decreases. B It increases, because the puddle gets shallower. C It increases, because the surface area decreases.

D It remains constant. [Nov-2004] / [Nov-2009]

16-

What will not affect the rate of evaporation from the surface of a liquid?

A depth of the liquid B draughts above the surface of the liquid

C surface area of the liquid D temperature of the liquid [Nov-2005]

17-

A hot liquid is carefully poured into a beaker. The graph shows how its temperature changes as it cools towards room temperature.

Which processes are taking place at region X? A boiling and evaporation

B condensation only C evaporation only

D solidification and evaporation [Nov-2005]

18-

A substance consists of particles that are close together and moving past each other at random. The average speed of the particles is gradually increasing. What best describes the substance? A a gas being heated B a liquid being heated

19-

Some ice cubes are taken from a deep-freeze and placed in a metal container. The container is heated at a constant rate and readings of temperature and time are taken. The results are recorded on a graph. Which temperature corresponds to 0 °C?

C

[May-2006]

20-

What conditions of temperature and surface area would produce the most rapid evaporation from a pool of water on a road surface?

temperature surface area

A high large

B high small

C low large

D low small

[Nov-2006]

21-

The energy required to change liquid water into water vapour at the same temperature is called

latent heat of vaporisation. What does this energy do?

A increases the average separation of the water molecules B increases the average speed of the water molecules C raises the temperature of the air near the water

D splits the water molecules into their separate atoms [Nov-2006]

22-

A 2 kW kettle containing boiling water is placed on a balance. It is left there and continues to boil for 5 minutes. The balance reading changes by 0.2 kg.

What does this information give as a value for the specific latent heat of vaporisation of water? A 2000 J / kg B 3000 J / kg C 50 000 J / kg D 3 000 000 J / kg [Nov-2006]

23-

On a hot day, a drink in a bottle can be kept cool by standing it in a bowl of water and placing a

wet cloth over it.

Why is the drink kept cool?

A Hot air cannot escape from the bottle.

B The cloth conducts heat from the bottle into the water. C The drink cannot evaporate from the bottle.

24-

The liquid in a puddle evaporates and this causes its temperature to change. How does the temperature of the liquid change and why?

change reason

A decreases less energetic molecules leave the liquid B decreases more energetic molecules leave the liquid C increases less energetic molecules leave the liquid D increases more energetic molecules leave the liquid [May-2010]

25-

An ice-cube has a mass of 7.50g. The ice-cube is at 0°C.Heat from the surroundings reaches the ice-cube at an average rate of 1.25 J/s. How long does it take for all of the ice to melt?

(specific latent heat of fusion of ice = 333 J/g)

A 35.5s B 55.5s C 2000s D 3120s [May-2010]

26-

A hot liquid is poured into a beaker. The graph shows how its temperature changes as it cools towards room temperature.

Which processes are taking place at region X?

A boiling and evaporation B condensation only C evaporation only D solidification and evaporation [Nov-2010]

PAPER-2 Theory

1-

Fig. 9.1 shows a refrigerator.

Inside the pipes in the ice-box, a liquid boils and takes in latent heat. The gas condenses in the pipes at the back of the refrigerator and thermal energy (heat) leaves through the black metal fins.

(a)

(i) State one similarity and one difference between boiling and evaporation.

(ii) Explain, in terms of the molecules involved, why latent heat is needed to boil the liquid.

(i) Explain how the ice box at the top of the refrigerator keeps the whole of the food compartment cool.

(ii) Explain why the fins are black.

2-

a) The table below describes the conditions of the molecules of a substance in each of the three states of matter, solid, liquid and gas.

In the right-hand column, write the state of the substance that is described in the lefthand

column.

(b) (i) What is the state of matter just before a substance boils? (ii) Describe what happens to the molecules during boiling. (c) (i) What is the state of matter just before a substance melts?

(ii) Aluminium melts at 660 °C. At what temperature does it freeze?

3-

Fig. 10.1 is a full-scale drawing of a small aluminium bar.

(a) Describe how the density of aluminium may be determined using the bar. In your account

(i) describe the readings to be taken,

(ii) state the instruments used to make the readings,

(iii) describe how the density is calculated from the readings. (b) The bar is placed in a small furnace.

In document o Level Worksheets PHYSICS. (Page 127-133)