# Balbharati solutions for Physics 11th Standard Maharashtra State Board chapter 7 - Thermal Properties of Matter [Latest edition]

#### Chapters ## Chapter 7: Thermal Properties of Matter

Exercises
Exercises [Pages 140 - 141]

### Balbharati solutions for Physics 11th Standard Maharashtra State Board Chapter 7 Thermal Properties of Matter Exercises [Pages 140 - 141]

Exercises | Q 1. (i) | Page 140

Choose the correct option.

Range of temperature in a clinical thermometer, which measures the temperature of the human body, is

• 70º C to 100º C

• 34º C to 42º C

• 0º F to 100º F

• 34º F to 80º F

Exercises | Q 1. (ii) | Page 140

Choose the correct option.

A glass bottle completely filled with water is kept in the freezer. Why does it crack?

• Bottle gets contracted

• Bottle is expanded

• Water expands on freezing

• Water contracts on freezing

Exercises | Q 1. (iii) | Page 140

Choose the correct option.

If two temperatures differ by 25° C on Celsius scale, the difference in temperature on Fahrenheit scale is

• 65°

• 45°

• 38°

• 25°

Exercises | Q 1. (iv) | Page 140

Choose the correct option.

If α, β and γ are coefficients of linear, area l and volume expansion of a solid then

• α : β : γ = 1 : 3 : 2

• α : β : γ = 1 : 2 : 3

• α : β : γ = 2 : 3 : 1

• α : β : γ = 3 : 1 : 2

Exercises | Q 1. (v) | Page 140

Choose the correct option.

Consider the following statements-

(I) The coefficient of linear expansion has dimension K-1.

(II) The coefficient of volume expansion has dimension K-1.

• I and II are both correct

• I is correct but II is wrong

• II is correct but I is wrong

• I and II are both wrong

Exercises | Q 1. (vi) | Page 140

Choose the correct option.

Water falls from a hight of 200 m. What is the difference in temperature between the water at the top and bottom of a waterfall given that the specific heat of water is 4200 J kg-1 °C-1?

• 0.96° C

• 1.02° C

• 0.46° C

• 1.16° C

Exercises | Q 2. (i) | Page 140

Clearly, state the difference between heat and temperature?

Exercises | Q 2. (ii) | Page 140

How a thermometer is calibrated?

Exercises | Q 2. (iii) | Page 140

What are different scales of temperature? What is the relation between them?

Exercises | Q 2. (iv) | Page 140

What is absolute zero?

Exercises | Q 2. (v) | Page 140

Derive the relation between three coefficients of thermal expansion.

Exercises | Q 2. (vi) | Page 140

State applications of thermal expansion.

Exercises | Q 2. (vii) | Page 140

Why do we generally consider two specific heats of a gas?

Exercises | Q 2. (viii) | Page 140

Are freezing point and melting point same with respect to change of state? Comment.

Exercises | Q 2. (ix) | Page 140

Define Sublimation.

Exercises | Q 2. (ix) | Page 140

Define Triple point.

Exercises | Q 2. (x) | Page 140

Exercises | Q 2. (xi) | Page 140

Define coefficient of thermal conductivity.

Exercises | Q 2. (xi) | Page 140

Derive its expression for the coefficient of thermal conductivity.

Exercises | Q 2. (xii) | Page 140

Give any four applications of thermal conductivity in everyday life.

Exercises | Q 2. (xiii) | Page 140

Explain the term thermal resistance. State its SI unit and dimensions.

Exercises | Q 2. (xiv) | Page 140

How heat transfer occurs through radiation in absence of a medium?

Exercises | Q 2. (xv) | Page 140

State Newton’s law of cooling and explain how it can be experimentally verified.

Exercises | Q 2. (xvi) | Page 140

What is thermal stress?

Exercises | Q 2. (xvi) | Page 140

Give an example of the disadvantages of thermal stress in practical use?

Exercises | Q 2. (xvii) | Page 140

Which materials can be used as thermal insulators and why?

Exercises | Q 3. (i) | Page 140

Solve the following problem.

A glass flask has a volume 1×10-4 m3. It is filled with a liquid at 30 ºC. If the temperature of the system is raised to 100 ºC, how much of the liquid will overflow. (Coefficient of volume expansion of glass is 1.2 × 10-5 (ºC)-1 while that of the liquid is 75 × 10-5 (ºC)-1).

Exercises | Q 3. (ii) | Page 140

Solve the following problem.

Which will require more energy, heating a 2.0 kg block of lead by 30 K or heating a 4.0 kg block of copper by 5 K?
(slead = 128 J kg–1 K–1, "s"_"copper" = 387 J kg–1 K–1)

Exercises | Q 3. (iii) | Page 140

Solve the following problem.

Specific latent heat of vaporization of water is 2.26 × 106 J/kg. Calculate the energy needed to change 5.0 g of water into steam at 100 ºC.

Exercises | Q 3. (iv) | Page 141

Solve the following problem.

A metal sphere cools at the rate of 0.05 ºC/s when its temperature is 70 ºC and at the rate of 0.025 ºC/s when its temperature is 50 ºC. Determine the temperature of the surroundings and find the rate of cooling when the temperature of the metal sphere is 40 ºC.

Exercises | Q 3. (v) | Page 141

Solve the following problem.

The volume of a gas varied linearly with absolute temperature if its pressure is held constant. Suppose the gas does not liquefy even at very low temperatures, at what temperature the volume of the gas will be ideally zero?

Exercises | Q 3. (vi) | Page 141

Solve the following problem.

In olden days, while laying the rails for trains, small gaps used to be left between the rail sections to allow for thermal expansion. Suppose the rails are laid at room temperature 27 °C. If maximum temperature in the region is 45 °C and the length of each rail section is 10 m, what should be the gap left given that α = 1.2 × 10–5K–1 for the material of the rail section?

Exercises | Q 3. (vii) | Page 141

Solve the following problem.

A blacksmith fixes iron ring on the rim of the wooden wheel of a bullock cart. The diameter of the wooden rim and the iron ring are 1.5 m and 1.47 m respectively at room temperature of 27 °C. To what temperature the iron ring should be heated so that it can fit the rim of the wheel? (αiron = 1.2 × 10–5K–1).

Exercises | Q 3. (viii) | Page 141

Solve the following problem.

In a random temperature scale X, water boils at 200 °X and freezes at 20 °X. Find the boiling point of a liquid in this scale if it boils at 62 °C.

Exercises | Q 3. (ix) | Page 141

Solve the following problem.

A gas at 900 °C is cooled until both its pressure and volume are halved. Calculate its final temperature.

Exercises | Q 3. (x) | Page 141

Solve the following problem.

An aluminium rod and iron rod show 1.5 m difference in their lengths when heated at all temperature. What are their lengths at 0 °C if coefficient of linear expansion for aluminium is 24.5 × 10–6/°C and for iron is 11.9 × 10–6/°C?

Exercises | Q 3. (xi) | Page 141

Solve the following problem.

What is the specific heat of metal if 50 cal of heat is needed to raise 6 kg of the metal from 20°C to 62 °C?

Exercises | Q 3. (xii) | Page 141

Solve the following problem.

The rate of flow of heat through a copper rod with temperature difference 30 °C is 1500 cal/s. Find the thermal resistance of copper rod.

Exercises | Q 3. (xiii) | Page 141

Solve the following problem.

An electric kettle takes 20 minutes to heat a certain quantity of water from 0 °C to boiling point. It requires 90 minutes to turn all the water at 100 °C into steam. Find the latent heat of vaporization. (Specific heat of water = 1 cal/g °C)

Exercises | Q 3. (xiv) | Page 141

Solve the following problem.

Find the temperature difference between two sides of a steel plate 4 cm thick, when the heat is transmitted through the plate at the rate of 400 k cal per minute per square meter at a steady state. Thermal conductivity of steel is 0.026 kcal/m s K.

Exercises | Q 3. (xv) | Page 141

Solve the following problem.

A metal sphere cools from 80 °C to 60 °C in 6 min. How much time with it take to cool from 60 °C to 40 °C if the room temperature is 30 °C?

## Chapter 7: Thermal Properties of Matter

Exercises ## Balbharati solutions for Physics 11th Standard Maharashtra State Board chapter 7 - Thermal Properties of Matter

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Concepts covered in Physics 11th Standard Maharashtra State Board chapter 7 Thermal Properties of Matter are Specific Heat Capacity, Heat and Temperature, Introduction to Thermal Properties of Matter, Measurement of Temperature, Absolute Temperature and Ideal Gas Equation, Thermal Expansion, Calorimetry, Change of State, Heat Transfer, Newton’s Law of Cooling.

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