Question 12 Marks
Answer
View full question & answer→- Freezing
- Vaporization
- Condensation
- Deposition
Questions
[2 Mark Questions]
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29 questions · timed · auto-graded
Question 22 Marks
An iron ball requires 9000 J heat energy to raise its temperature by 10°C. Calculate the heat capacity of the iron bail.
Answer
View full question & answer→Given, $Q =9000 J$
$
\Delta T =10^{\circ} C
$
Heat capacity, $C =\frac{Q}{\Delta T}=\frac{9000}{10}=900 J ^{\circ} C ^{-1}$
$
\Delta T =10^{\circ} C
$
Heat capacity, $C =\frac{Q}{\Delta T}=\frac{9000}{10}=900 J ^{\circ} C ^{-1}$
Question 32 Marks
A body of mass 750 g requires 13,500 J of heat energy in order to raise its temperature from 25 °C to 55 °C. Calculate its specific heat capacity.
Answer
View full question & answer→Given
$m =750 g =0.750 kg$
$\Delta T (55-25)^{\circ} C =30^{\circ} C$
$Q =13,500 J$
$Q = mC \Delta T$
or
$C =\frac{ Q }{m \Delta T }=\frac{13,500}{0.750 \times 30}$
$=600 J Kg ^{-1}$
$m =750 g =0.750 kg$
$\Delta T (55-25)^{\circ} C =30^{\circ} C$
$Q =13,500 J$
$Q = mC \Delta T$
or
$C =\frac{ Q }{m \Delta T }=\frac{13,500}{0.750 \times 30}$
$=600 J Kg ^{-1}$
Question 42 Marks
What is the rise in temperature of 5 kg of water if it is given $84,000 J$ heat energy? Specific heat capacity of water $4200 J Kg ^{-1}{ }^{\circ} C ^{-1}$.
Answer
View full question & answer→Given, $m =5 kg$
$Q =84,000 J$
$C =4200 J Kg ^{-1}{ }^{\circ} C ^{-1}$
Let rise in the temperature be $\Delta T$.
Heat energy $( Q )= mC \Delta T$
$84,000=5 \times 4200 \times \Delta T$
$\Delta T =\frac{84000}{5 \times 4200}$
$=4^{\circ} C$
$Q =84,000 J$
$C =4200 J Kg ^{-1}{ }^{\circ} C ^{-1}$
Let rise in the temperature be $\Delta T$.
Heat energy $( Q )= mC \Delta T$
$84,000=5 \times 4200 \times \Delta T$
$\Delta T =\frac{84000}{5 \times 4200}$
$=4^{\circ} C$
Question 52 Marks
Distinguish between evaporation and vaporization.
Answer
View full question & answer→| Evaporation | Vaporization |
| 1. Evaporation takes place at all temperature. | 1. Vaporization takes place at fixed temperature. |
| 2. Slow and gradual process | 2. Violent and rapid process. |
| 3. Takes place at the surface of the liquid | 3. Takes place through the entire liquid. |
Question 62 Marks
Arrange the following in order of decreasing expansion of heating : Steel, milk, air.
Answer
View full question & answer→Air, milk, steel.
Question 72 Marks
Distinguish between heat capacity and specific heat capacity.
Answer
View full question & answer→| Heat capacity | Specific heat capacity |
| 1. It is the heat required to raise the temperature of a given mass of a substance through $1^{\circ} C$. | 1. It is the heat required to raise the temperature of 1 g of a substance through $1^{\circ} C$. |
| 2. It depends on the mass of the body | 2. It does not depend on the mass of the body. |
| 3. Its unit is $J^{\circ} C ^{-1}$ | 3. Its unit is $JKg ^{-10} C ^{-1}$ |
Question 82 Marks
Can convection take place in solids? Why?
Answer
View full question & answer→- No. The molecules in a solid are only free to vibrate about their fixed positions.
- For convection to take place, the molecules need to move carrying the heat with them.
- Hence convection cannot take place in solids.
Question 92 Marks
Why do we wear woolen clothes in winter?
Answer
View full question & answer→- The fibers of wool have the property of trapping air in between them.
- In trapping the air, woolen clothes do not allow the heat to flow away from the body, which would then become cold.
- Besides, wool is poor conductor of heat. So this property further prevents heat from leaving the body.
Question 102 Marks
Mention the applications of radiation in daily life.
Answer
View full question & answer→- Heat energy from the Sun reaches the Earth by radiation.
- While standing near fire we feel the heat which is transferred as radiation.
- Black surfaces absorb heat radiation. So that the bottom of the cooking vessels are painted black.
- White color reflects heat radiation. That’s why we are advised to wear white cloth during summer.
Question 112 Marks
Define radiation.
Answer
View full question & answer→Radiation is defined as the way of heat transfer from one place to another in the form of electromagnetic waves.
Question 122 Marks
Mention the applications of convection in daily life.
Answer
View full question & answer→- Formation of land breeze and sea breeze is due to convection of air.
- Wind flows from one region to another region by convection.
- In hot air balloons heat is transferred by convection and so the balloon raises.
- In refrigerators, cool air moves downward and replaces the hot air because of convection.
Question 132 Marks
What is transfer of heat?
Answer
View full question & answer→If heat energy is supplied to any substance, it will be transferred from one part of the substance to another part.
Question 142 Marks
You would have noticed some space being left in railway tracks. Why?
Answer
View full question & answer→- It is because railway tracks which are made up of iron (metal) expand during summer.
- When there is a gap, there will not be any damage in the track due to expansion of the metal rod.
Question 152 Marks
What is the function of silvered wall in a thermos flask?
Answer
View full question & answer→The silvered walls reflect radiated heat back to the liquid in the flask.
Question 162 Marks
Name some appliances which uses thermostat.
Answer
View full question & answer→Central heater in a room, air conditioner, water heater, oven and refrigerators.
Question 172 Marks
What is the function of a thermostat in a device?
Answer
View full question & answer→Thermostat functions both as the sensor and the controller of a thermal system.
Question 182 Marks
Mention the SI unit of specific heat capacity?
Answer
View full question & answer→The SI unit of specific heat capacity is $J Kg ^{-1} K ^{-1}$.
Question 192 Marks
What is the SI unit of heat capacity?
Answer
View full question & answer→The SI unit of heat capacity is $JK ^{-1}$
Question 202 Marks
Which color absorb heat radiation and which color reflects heat radiation?
Answer
View full question & answer→Black surfaces absorb heat radiation. White color reflects heat radiation.
Question 212 Marks
What are the various modes of transfer of heat?
Answer
View full question & answer→- Conduction
- Convection
- Radiation
Question 222 Marks
What is the principle of calorimetry?
Answer
View full question & answer→Heat lost by the hot body is equal to the heat gained by the cold body.
Question 232 Marks
Mention the factors affecting the flow of heat.
Answer
View full question & answer→- Mass and materials of the bodies in contact.
- Difference in their temperatures.
Question 242 Marks
Write the relation between joule and calorie.
Answer
View full question & answer→1 Calorie = 4.186 J.
1 K cal = 4186 J = 4.186 KJ.
1 K cal = 4186 J = 4.186 KJ.
Question 252 Marks
Name three types of heat transfer.
Answer
View full question & answer→- Conduction
- Convection
- Radiation
Question 262 Marks
What are the effects of heat?
Answer
View full question & answer→- Expansion
- Increase in temperature
- Change in state
Question 272 Marks
What are the applications of conduction in our daily life?
Answer
View full question & answer→- We cook food in vessels made up of metals. When the vessel is heated, heat is transferred from the metal to the food.
- When we iron dresses heat is transferred from the iron to the cloth.
- Handles of cooking utensils are made up of plastic or wood because they are poor conductors of heat.
- The temperature inside the igloo (snow house) is warm because snow is a poor conductor of heat.
Question 282 Marks
The heat capacity of the vessel of mass 100 kg is 8000 J/°K. Find its specific heat capacity.
Answer
View full question & answer→Specific heat capacity, $C =\frac{ Q }{\operatorname{mx\Delta } T }$
Here, m = 100 kg
Heat capacity $=\frac{ Q }{\Delta T }$ = 8000 J/°C = 8000 J/K
$C =\frac{ Q }{ mx \Delta T }=$ 100 x 8000 J = 8,00,000 JKg -1 K-1
Here, m = 100 kg
Heat capacity $=\frac{ Q }{\Delta T }$ = 8000 J/°C = 8000 J/K
$C =\frac{ Q }{ mx \Delta T }=$ 100 x 8000 J = 8,00,000 JKg -1 K-1
Question 292 Marks
Numerical Problems.
An iron ball requires 1000 J of heat to raise its temperature by 20°C. Calculate the heat capacity of the ball.
An iron ball requires 1000 J of heat to raise its temperature by 20°C. Calculate the heat capacity of the ball.
Answer
View full question & answer→Heat capacity $C ^{\prime}=\frac{ Q }{\Delta T }$
Here, A = 1000 J
T = 20°C – 0°C = 20°C = 20 k
$C=\frac{1000}{20}$ = 50 JK-1
Here, A = 1000 J
T = 20°C – 0°C = 20°C = 20 k
Here, A = 1000 J
T = 20°C – 0°C = 20°C = 20 k
$C=\frac{1000}{20}$ = 50 JK-1
Here, A = 1000 J
T = 20°C – 0°C = 20°C = 20 k