# Class 9 Physics Thermal Properties of Matter 4. a) Explain the effects of large specific heat of water with examples from our daily life.

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##### 4. a) Explain the effects of large specific heat of water with examples from our daily life.

iii. Mercury is used as thermometric material because it has(a) uniform thermal expansion(b) low freezing point(c) small heat capacity(d) all the above properties

b) Why small gaps are left at the joints of sections of railway tracks? Explain the phenomenon involved in it.

8.1 Encircle the correct answer from the given choices.i. Water freezes at(a) 0^{\circ} \mathrm{F} (b) 32^{\circ} \mathrm{F} (c) -273 \mathrm{~K} (d) 0 \mathrm{~K}

5. A fixed temperature at which a pure liquid boils is calleda) melting pointb) freezing pointc) boiling pointd) Both (a) and (b).

c) Convert 212^{\circ} \mathrm{F} into Celsius and Kelvin.

8.8 Define specific heat. How would you find the specific heat of a solid?

EXAMPLE 8.2Change 300 \mathrm{~K} on Kelvin scale into Celsius scale of temperature.

b) 2 \mathrm{~kg} of copper requires 2050 \mathrm{~J} of heat to raise its temperature through 10^{\circ} \mathrm{C} . Calculate the heat capacity of the sample.

2. Heat capacity is the product of mass anda) Boiling pointb) Freezing pointc) Energyd) Specific heat of material

14. a) Draw the diagram showing real and apparent expansion of liquid. Label the diagram properly.

11. Write down the freezing and boiling points of followingi) Acetic acidii) Benzeneiii) Chloroformiv) Water

13. An iron block of volume 3 \mathrm{~m}^{3} is heated so that its temperature changes from 25^{\circ} \mathrm{C} to 100^{\circ} \mathrm{C} . If the coefficient of linear expansion of iron is 11 \times 10^{-6}{ }^{\circ} \mathrm{C}^{-1} . What will be the new volume of the iron block after heating ?

9. Evaporation can occur ata) freezing pointb) melting pointc) boiling pointd) all temperatures

10. Rate of evaporation of a liquid can be increased bya) increasing humidityb) decreasing temperaturec) increasing its boiling pointd) decreasing atmospheric pressure

8.5 How much heat is required to increase the temperature of 0.5 \mathrm{~kg} of water from 10^{\circ} \mathrm{C} to 65^{\circ} \mathrm{C} ? (115500 \mathrm{~J})

11. Linear thermal expansion of a solid depends upona) increase in temperatureb) originallengthc) properties of materiald) all of these

8.10 Find the temperature of water after passing 5 \mathrm{~g} of steam at 100^{\circ} \mathrm{C} through 500 \mathrm{~g} of water at 10^{\circ} \mathrm{C} . \left(16.2^{\circ} \mathrm{C}\right) (Note: Specific heat of water is 4200 \mathrm{Jkg}^{-1} \mathrm{~K}^{-1} Latent heat of vaporization of water is \left.2.26 \times 10^{6} \mathrm{Jkg}^{-1}\right) .

vi. What will be the value of p for a solid for which a has a value of 2 \times 10^{-5} \mathrm{~K}^{-1} ? (a) 2 \times 10^{5} \mathrm{~K}^{-1} (b) 6 \times 10^{-5} \mathrm{~K}^{-1} (c) 8 \times 10^{-15} \mathrm{~K}^{-1} (d) 8 \times 10^{-5} \mathrm{~K}^{-1}

Worked Example 1The temperature of Hyderabad on a hot day is 45 degree Celsius \left(45^{\circ} \mathrm{C}\right) . What will be its equivalent temperature on Fahrenheit Scale?

EXAMPLE 8.1What will be the temperature on Kelvin scale of temperature when it is 20^{\circ} \mathrm{C} on Celsius scale?

c) How much heat is required to boil 3 \mathrm{~kg} water which is initially 10^{\circ} \mathrm{C} ?

EXAMPLE 8.5 A container has 2.5 litres of water at 20^{\circ} \mathrm{C} . How much heat is required to boil the water?

EXAMPLE 8.6 A brass rod is 1 \mathrm{~m} long at 0^{\circ} \mathrm{C} . Find its length at 30^{\circ} \mathrm{C} . (Coefficient of linear expansion of brass =1.9 \times 10^{-5} \mathrm{~K}^{-1} )

EXAMPLE 8.7 Find the volume of a brass cube at 100^{\circ} \mathrm{C} whose side is 10 \mathrm{~cm} at 0^{\circ} \mathrm{C} . (coefficient of linear thermal expansion of brass =1.9 \times 10^{-5} \mathrm{~K} 1 ).

viii. Which of the following affects evaporation?(a) temperature(b) surface area of the liquid(c) wind(d) all of the above