NIOS Class 10 Science & Technology Chapter 14 Solution

NIOS Class 10 Science & Technology Chapter 14 Solution – Thermal Energy

NIOS Class 10 Science & Technology Solution Chapter 14 Thermal Energy. NIOS Class 10 Science & Technology Chapter 14 Question Answers Download PDF. NIOS Class 10 Science Notes.

NIOS Class 10 Science & Technology Chapter 14 Solution

 Board NIOS Class 10th (Secondary) Subject Science and Technology (214) Topic Question Answer, Solution, Notes

CHAPTER: – 14.

(THERMAL ENERGY)

INTEXT QUESTIONS 14.1

State whether the following statements are true or false:

(i) Heat can be measured in kelvin.

Ans: – False.

(ii) –30° F is a lower temperature than –30° C.

Ans: – False.

(iii) The numerical value of temperature of any hot body measured on kelvin’s scale is always higher than the value on Fahrenheit scale.

Ans: – True.

(iv) Thermal energy can be measured either in calories or in joules.

Ans: – True.

(v) Pure alcohol can also be used as thermometric liquid.

Ans: – True.

(vi) A body is felt cold when heat flows from our body to that body.

Ans: – True.

INTEXT QUESTIONS 14.2

Fill in the blanks with the correct choice

1)A bimetallic strip is used as a thermostat in the electrical device named……refrigerator……….. (Electric bulb, T.V., refrigerator).

2)Melting point of 1 kg wax will be …same as………….. the melting point of 2 kg wax(double, half, same as).

3)Latent heat of evaporation is measured in ………J/kg…….. (J, J/K, J/kg).

4)1 kg steam at 100 °C has 2260 J ……more……….. heat than water at 100 °C(more, less).

5)The cubical expansively of a substance is …three times………….. its linear expensively(equal to, two times, three times)

6)The expansivity of ………gases…….. is maximum. (solids, liquids, gases).

INTEXT QUESTIONS 14.3

Choose the correct alternative

1) Two iron balls of radii r and 2r are heated to the same temperature. They are dropped in two different ice boxes A and B respectively. The mass of ice melted

(a) will be same in the two boxes.

(b) in A will be twice than in B.

(c) in B will be twice than that in A.

(d) in B will be four times than that in A.

Ans: – Option (d).

2)An iron ball A of mass 2 kg at temperature 20°C is kept in contact with another iron ball B of mass 1.0 kg at 20°C. The heat energy will flow

(a) from A to B only

(b) from B to A only

(c) in neither direction

(d) Initially from A to B and then from B to A.

Ans: – Option (c).

3)When solid ice at 0°C is heated, its temperature

(a) rises (b) falls

(c) does not change until whole of it melts.

(d) first rises then falls back to 0°C.

Ans: – Option (c).

4)When steam at 100°C is heated its temperature

(a) does not change. (b) increases

(c) decreases (c) none of these.

Ans: – Option (b).

5) Specific heat of aluminium is almost two times the specific heat of copper. Equal amount of heat is given to two pieces of equal masses of copper and iron respectively. Rise in temperature of

(a) Copper will be equal to that of aluminium.

(b) Copper will be twice the rise in temperature of aluminium.

(c) Copper will be half the rise in temperature of aluminium.

(d) Copper will be four times the rise in temperature of aluminium.

Ans: – Option (b).

6) Equal heat is given to three pieces of copper A, B, and C having masses in the ratio 1:2:3. The rise in temperature will be in the order

(a) A > B > C (b) B > C > A

(c) C > B > A (d) A > C > B.

Ans: – option (a).

TERMINAL EXERCISE

1) Distinguish clearly between heat and temperature.

Ans: –The heat and temperature of the different object are mentioned by different way. The heat is determined by the thermal energy but temperature is determined by the molecular kinetic energy.

2) During change of state: (i) Is there a rise in temperature of the material on heating it? and (ii)What happens to the heat we supply?

Ans: – Yes there will be rise in temperature of the material on heating. As when the state is changes to the other state the molecules in it will have more kinetic energy as compared to previous.

3) Name the factors on which the thermal expansion of a wire depends.

Ans: – The thermal expansion of wire is dependent on the various factor like-

• The area of the wire.
• The length of the wire.
• Surrounding temperature.
• Material of the wire.

4) Give any two uses of a bimetallic strip.

Ans: – There are two different elements in a bimetallic strip. This bimetallic strip isused in the displacement changes by mechanical stretch.These two elements have different temperature.

5) If you have an uncalibrated mercury thermometer how will you calibrate it into a

(a) Celsius thermometer (b) Fahrenheit thermometer.

Ans: – There present a bulb in the thermometer which get equilibrium at standard temperature when it kept in the water or ice try to make in equilibrium. There is a difference between the Celsius and Fahrenheit thermometer as Fahrenheit thermometer is more superior.

6) Explain the following:

(i) Why is mercury used as a thermometric liquid?

(ii) Why does a bimetallic strip bend on heating?

(iii) Why does steam at 100°C gives more severe burns than water at100°C?

(iv) Why do we use ice for cooling our drinks and not water at 0°C.?

Ans: – (i)The element which is used in thermometer is mercury as this have some specific quality like it quickly heated up and get down and don’t stick in the wall.

(ii)There are two different elements in bimetallic strip and both have different temperature.

(iii) Because of the latent heat at 100℃ of steam is more than the water so this is more severe than the water at 100℃.

(iv)As the specific heat of ice ore than the other so this is used.

7) Why is the heat given at the time of change of state called latent heat?

Ans: – As when the more heated or the object has more temperature is transfer from this object to the other. And always this happens because of trend of the transferring of high temperature to low temperature.

8) A certain amount of water is heated at a constant rate. The time to bring it to boiling is t1 and the time required from beginning of boiling to boiling off the whole amount is t2. Which is greater t1or t2? Why?

Ans: – We all know that time in heating the object at certain temperature at starting is law as compared to the final temperature where the liquid gets boiled.

9) At what temperature the numerical value of temperature on Fahrenheit scale will be double the value on Celsius scale.

Ans: – We know, C/5=F-32/9.

Let, c=x  and  F=2x,

So, x/5=2x -32/9;

Or, x= 160℃.

The value in Fahrenheit scale is 320℃.

10) A 50 cm silver bar shortens by 1.0 mm when cooled. How much was it cooled?

(Given: – coefficient of linear expansion of silver = 18 × 10-6 per degree Celsius)

Ans: –

11) How much heat energy is required to change 200 g of ice at –20°C to water at 70°C?

(Given: Latent heat of fusion of ice = 335 kJ kg–1, and specific heat of ice =2100 J kg–1 °C–1, specific heat of water = 4.2 kJ kg–1 °C–1)

Ans: –

Updated: February 24, 2022 — 4:02 pm