#### Chapters

Chapter 2 - Work, Energy and Power

Chapter 3 - Machines

Chapter 4 - Refraction of Light at Plane Surfaces

Chapter 5 - Refraction through a Lens

Chapter 6 - Spectrum

Chapter 7 - Sound

Chapter 8 - Current Electricity

Chapter 9 - Electrical Power and Household Circuits

Chapter 10 - Electro-Magnetism

Chapter 11 - Calorimetry

Chapter 12 - Radioactivity

## Chapter 11 - Calorimetry

#### Page 0

Define the term heat.

Name the S.I. unit of heat.

Define the term calorie. How is it related to joule?

Define one kilo-calorie of heat.

Define temperature and name its S.I. unit.

Differentiate between heat and temperature.

Define calorimetry ?

Define the term heat capacity and state its S.I. unit.

Define the term specific heat capacity and state its S.I. unit.

How is heat capacity of a body related to specific heat capacity of its substance?

Differentiate between heat capacity and specific heat capacity.

Name a liquid which has the highest specific heat capacity.

Write the approximate value of specific heat capacity of water in S.I. unit.

What do you mean by the following statement :

The heat capacity of a body is `50JK^-1` ?

What do you mean by the following statement :

The specific heat capacity of copper is `0. 4 Jg^-1K^-1`.

Name three factors on which heat energy absorbed by a body depends and state how does it

depend on them.

Write the expression for the heat energy Q received by the substance when m kg of substance

of specific heat capacity c `Jkg^-1 k^-1` is heated through Δt° C.

Same amount of heat is supplied to two liquid A and B. The liquid A and B. The liquid A

shows a greater rise in temperature. What can you say about the heat capacity of A as compared

to that of B?

Two metallic blocks P and Q of masses in ratio 2 : 1 are given same amount of heat. If their

temperature rise by same amount, compare their specific heat capacities.

Why do the farmers fill their fields with water on a cold winter night?

Discuss the role of high specific heat capacity of water with reference to climate in coastal areas.

Water is used in hot water bottles for fomentation give a reason.

Water is used as an effective coolant. Give reason.

Give one example where high specific heat capacity of water is used as coolant ?

Give one example where high specific heat capacity of water is used as heat reservoir ?

What is a calorimeter? Name the material of which it is made of. Give two reasons for using the material stated by you.

Why is the base of a cooking pan generally made thick?

What is the principle of method of mixture (or principle of calorimetry)? Name the law on which

this principle is based.

A mass m1 of a substance of specific heat capacity c1 at temperature t1 is mixed with a mass m2

of other substance of specific heat capacity c2 at a lower temperature t2. Deduce the expression

for the temperature of the mixture. State the assumption made, if any.

Describe a method to determine the specific heat capacity of a solid, like a piece of copper ?

How will you determine the specific heat capacity of a liquid like olive oil by the method of mixtures?

In an experiment to determine the specific heat capacity of a solid following operations were

made:

Mass of calorimeter + stirrer = x kg

Mass of water = y kg

Initial temperature of water t1℃

Mass of solid = z kg

Temperature of solid = t2 ℃

Temperature of mixture = t ℃

Specific heat capacity of calorimeter and water are c1 and c2 respectively. Express the specific

heat capacity c of the solid in terms of the above data.

A heater of power P watt raises the temperature of m kg of a liquid by Δt K in time t s. Express

the specific heat capacity of liquid in terms of above data.

#### Page 0

**MUTIPLE CHOICE QUESTION:**

The S.I. unit of heat capacity is:

(a)` J kg^-1`

(b) `J K^-1`

(c) `J kg^-1 K^-1`

(d) `cal ℃^-1`

MUTIPLE CHOICE QUESTION:

The S.I. unit of specific heat capacity is:

(a) `J kg^-1`

(b) `J K^-1`

(c) `J kg^-1 K^-1`

(d) `kilocal kg^-1 ℃^-1`

**MUTIPLE CHOICE QUESTION:**

The specific heat capacity of water is:

(a) `4200 J kg^-1 K^-1`

(b) `420 J g^-1 K^-1`

(c) `0.42 J g^-1 K^-1`

(d) `4.2 J kg^-1 K^-`1

#### Page 0

By imparting heat to a body its temperature rises by 15° C. what is the corresponding rise in temperature on kelvin scale?

(a) Calculate the heat capacity of a copper vessel of mass 150g if the specific heat capacity of copper is `410 J kg^-1 K^-1`

(b) How much heat energy will be required to increase the temperature of the vessel in part (a) from 25°C to 35°C?

A piece of iron of mass 2.0 kg has a thermal capacity of `966 J K^-1`. Find : (1) heat energy needed to warm it by 15°C and (2) its specific heat capacity in S.I. unit.

Calculate the amount of heat energy required to raise the temperature of 100 g of copper from 20°C to 70°C. specific heat capacity of copper = `390 J kg^-1 K^-1`.

1300 J of heat energy is supplied to raise the temperature of 0.5 kg of lead from 20° C to 40°C.

Calculate the specific heat capacity of lead

Find the time taken by a 500 W heater to raise the temperature of 50 kg of material of specific

heat capacity `960 J kg^-1K^-1`, from 18°C to 38° C. assume that all the heat energy supplied by the heater is given to the material.

An electric heater of power 600 W raises the temperature of 4.0 kg of a liquid from 10.0 ℃ to

15.0 ℃ I 100 s. Calculate: (i) the heat capacity of 4.0 kg of liquid, (ii) the specific heat capacity

of the liquid.

0.5 kg of lemon squash at 30° C is placed in a refrigerator which can remove heat at an average

rate of `30 J s^-1`. How long will it take to cool the lemon squash to 5°C? Specific heat capacity of

squash = `4200 J kg^-1K^-1`

200 g mass of certain metal of 83°C is immersed in 300 g of water at 30°C the final temperature

is 33°C. Calculate the specific heat capacity of the metal Assume that the specific heat capacity

of water is `4.2 J g^-1K^-1`

45 g of water at 50°C in a beaker is cooled when 50 g of copper at 18° C is added to it. The contents are stirred till a final constant temperature is reached. Calculate this final temperature.The specific heat capacity of copper is `0.39 J g^-1K^-1` and that of water is `4.2 J g^-1K^-1` State theassumption used.

200 g of hot water at 80°C is added to 300 g of cold water at 10°C. Neglecting the heat taken by

the container, calculate the final temperature of the mixture of water. Specific heat capacity of

water = `4200 J kg^-1K^-1`

The temperature of 600 g of cold water rises by 15° C when 300 g of hot water at 50° C is added

to it. What was the initial temperature of the cold water?

1.0 kg of water is container in a 1.25 kW kettle Calculate the time taken for the temperature of water to rise from 25° C to its boiling point 100°C. Specific heat capacity of water = ` 4.2 J

g^-1K^-1`

#### Page 0

What do you understand by the change of phase of a substance?

Is there any change in temperature during the change of phase?

Does the substance absorb or liberate any heat energy during the change of phase?

Explain the terms melting ?

Explain the melting point ?

Describe an experiment to show that there is absorption of heat energy when the ice melts.

A substance undergoes (i) a change in its temperature, (ii) a change in its phase without change in its temperature. In each case, state the change in energy of molecules of the substance.

How does the average kinetic energy ?

How does the average potential energy of molecules of a substance change during its change in phase at a constant temperature?

State the effect of presence of impurity on the melting point of ice. Give one use of it.

State the effect of increase of pressure on the melting point of ice.

Fig 11. 11 shows the variation in temperature with time when some wax cools from the liquid phase to the solid phase.

(i) In which part of the curve, the wax is in liquid phase?

(ii) What does the part QS of the curve represent?

(iii) In which part of the curve, the wax will be the in the liquid as well as solid phase?

(iv) In which part of the curve, the wax is in solid phase?

The diagram in Fig 11.12 below shows the change of phase of a substance on a temperature time graph.

(a) What do the parts AB, BC, CD and DE represent?

(b) what is the melting points of the substance?

(c) what is the boiling points of the substance?

1 kg of ice at 0°C is heated at a constant rate and its temperature is recorded after every 30 s till steam is formed at 100℃. Draw a temperature time graph to represent the change of phase.

The melting point of naphthalene, a crystalline solid is 80℃ and the room temperature is 30℃. A sample of liquid naphthalene at 100℃ is cooled down to the room temperature. Draw a temperature time graph to represent this cooling.

Explain the term boiling ?

Explain the term boiling point ?

How is the volume of water affected when it boils at 100℃?

How is the boiling point of water affected when some salt is added to it?

What is the effect of increase in pressure on the boiling point of a liquid?

Write down the approximate range of temperature at which water boils in a pressure cooker.

It is difficult to cook vegetables on hills and mountains. Explain the reason.

Complete the following sentence:

When ice melts, its volume _________

Complete the following sentence:

Decrease in pressure over ice ________ its melting point.

Complete the following sentence:

Increase in pressure _________ the boiling point of water.

Complete the following sentence:

A pressure cooker is based on the principle that boiling point of water increases with the _________

Complete the following sentence :

The boiling point of water is defined as _________

What do you understand by the term latent heat?

Define the term specific latent heat of fusion of ice state its S.I unit.

Write the approximate value of specific latent heat of ice.

The specific latent heat of fusion of ice is 336 J g-1. Explain the meaning of its statement.

1 g ice of 0℃ melts to form 1 g water at 0℃. State whether the latent heat is absorbed or given out by ice.

Which has more heat: 1 g ice at 0℃ or 1g water 0℃? Give reason.

(a) Which requires more heat: 1 g ice at 0℃ or 1 g water at 0℃ to raise its temperature to 10℃?

(b) Explain your answer in part (a).

Ice cream appears coder to the mouth than water at 0℃. Give reason.

Why do bottled soft drinks get cooled, more quickly by the ice cubes than by the iced water, both at 0℃?

It is generally cold after a hail-storm then during and before the hail storm. Give reason.

The temperature of the surrounding starts falling when ice in a frozen lake starts melting. Give reason.

Explain the following:

The surrounding become pleasantly warm when water in a lake starts freezing in cold countries ?

Explain the following:

The heat supplied to a substance during it change of state, does not cause any rise in its temperature.

#### Page 0

The S.I. unit of specific latent heat is:

(a) `cal g^-1 `

(b) `cal g^-1K^-1`

(c)` J kg^-1 `

(d) `J kg^-1 K^-1`

The specific latent heat of fusion of water is:

(a)` 80 cal g^-1`

(b) `2260 J g^-1`

(c) `80 J g-1`

(d) `336 J kg^-1`

#### Page 0

10g of ice at 0℃ absorbs 5460 J of heat energy to melt and change to water at 50℃. Calculate the specific latent heat of fusion of ice. Specific heat capacity of water is `4200 J kg^-1 K^-1`

How much heat energy is released when 5.0 of water at 20℃ changes into ice at 0℃? Take

specific heat capacity of water =`4.2 J kg^-1 K^-1`, Specific latent heat of fusion of ice `336 J g^-1`

A molten metal of mass 150 g is kept at its melting point 800℃. When it is allowed to freeze at

the same temperature, it gives out 75,000 J of heat energy.

(a) What is the specific latent heat of the metal?

(b) If the specific heat capacity of metal is `200 J kg^-1 K^-1`, how much additional heat energy will

the metal give out in cooling to – 50 ℃?

A refrigerator converts 100g of water at 20℃ to ice at – 10℃ in 73.5 min. Calculate the average

the rate of heat extraction in watt. The specific heat capacity of water is `4.2 J kg^-1 K^-1` Specific latent heat of ice is 336 J g-1 and the specific heat capacity of ice if `2.1 J kg^-1 K^-1`.

In an experiment, 17g of ice is used to bring down the temperature of 40 g of water at 34℃ to its

freezing temperature. The specific heat capacity of water is `4.2 J kg^-1 K^-1`. Calculate the specific latent heat of ice. State one important assumption made in the above calculation.

Find the result of mixing 10 g of ice at - 10℃ with 10 g of water at 10℃. Specific heat capacity

of ice = `2.1 J kg^-1 K^-1`, Specific latent heat of ice = `336 J g^-1` and specific heat capacity of water

= `4.2 J kg^-1 K^-1`

A piece of ice of mass 40 g is added to 200 g of water at 50℃, Calculate the final temperature of

water when all the ice has melted. Specific heat capacity of water =`4200 J kg^-1 K^-1`, and specific latent heat of fusion of ice = `336 × 10^3 J kg^-1`.

250 g of water at 30℃ is contained in a copper vessel of mass 50g. Calculate the mass of ice

required to bring down the temperature of the vessel and its contents to 5℃. Given: specific

latent heat of fusion of ice = `336 xx 10^3J kg^-1`, specific heat capacity of copper = `400 J kg^-1 K^-1`,

specific heat capacity of water = `4200 J kg^-1 K^-1`

2 kg of ice melts when water at 100℃ is poured in a hole drilled in a block of ice. What mass of

water was used? Given: Specific heat capacity of water = `4200 J kg^-1 K^-1`, Lice = `336×10^3 J kg^-1`.

Calculate the total amount of heat energy required to convert 100g of ice at −10℃ completely into water at 100℃. Specific heat capacity of ice = `2.1 kg^-1 K^-1`, specific heat capacity of water = `4.2 J kg^-1 K^-1`, specific latent heat of ice = `336 J g^-1`

The amount of heat energy required to convert 1 kg of ice at – 10℃ to water at 100℃ is 7,77,000 J. Calculate the specific latent heat of ice. Specific heat capacity if ice = `2100 J kg^-1 K^-1`, Specific heat capacity of water = `4200 J kg^-1 K^-1`

#### Page 0

Explain the meaning of green house effect.

Name two green house gases ?

Name the radiations for which the green house gases are transparent ?

Name the radiations for which the green house gases are opaque ?

Name three fossil fuels that emit carbon dioxide into the atmosphere ?

How does green house effect help in keeping the temperature of earth’s surface suitable for living of human beings?

Give three reasons for the increase of green house gases.

State the effect of enhancement of green house effect.

What is meant by global warming?

State the impact of global warming on life on the earth.

How will rise in sea level affect population in coastal countries?

What impact will global warming have on the health of the affected population?

How will climate changes affect the various animal species?

What impact will climate changes have on the crops of food?

How will global warming disturb the ecological balance?

State three ways to minimize the global warming.

What is carbon tax?

Who shall pay carbon tax ?

#### Page 0

Without green house effect, the average temperature of earth’s surface would have been:

(a) – 18℃

(b) 33℃

(c) 0℃

(d) 15℃

The global warming has resulted:

(a) the increase in yield of crops

(b) the decrease in sea levels

(c) the decrease in human deaths

(d) the increase in sea levels