Q. What is the change in internal energy of a gas that absorbs 300 J of heat and does 100 J of work on the surroundings? (2020)
A.
200 J
B.
300 J
C.
400 J
D.
500 J
Show solution
Solution
Change in internal energy (ΔU) = Q - W = 300 J - 100 J = 200 J.
Correct Answer:
A
— 200 J
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Q. What is the change in internal energy of a system if 200 J of heat is added and 50 J of work is done by the system?
A.
150 J
B.
250 J
C.
200 J
D.
100 J
Show solution
Solution
Using the first law of thermodynamics, ΔU = Q - W = 200 J - 50 J = 150 J.
Correct Answer:
A
— 150 J
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Q. What is the change in internal energy of a system if 300 J of heat is added and 100 J of work is done by the system? (2021)
A.
200 J
B.
300 J
C.
400 J
D.
500 J
Show solution
Solution
Using the first law of thermodynamics: ΔU = Q - W = 300 J - 100 J = 200 J.
Correct Answer:
A
— 200 J
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Q. What is the efficiency of a Carnot engine operating between 300 K and 600 K? (2022)
A.
0.5
B.
0.33
C.
0.25
D.
0.67
Show solution
Solution
Efficiency = 1 - (T_c/T_h) = 1 - (300/600) = 0.5.
Correct Answer:
A
— 0.5
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Q. What is the efficiency of a Carnot engine operating between 500 K and 300 K? (2022)
A.
0.4
B.
0.5
C.
0.6
D.
0.7
Show solution
Solution
Efficiency = 1 - (T2/T1) = 1 - (300/500) = 0.4 or 40%.
Correct Answer:
C
— 0.6
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Q. What is the efficiency of a Carnot engine operating between a hot reservoir at 600 K and a cold reservoir at 300 K?
A.
0.5
B.
0.33
C.
0.25
D.
0.75
Show solution
Solution
Efficiency (η) = 1 - (T_c/T_h) = 1 - (300/600) = 0.5 or 50%.
Correct Answer:
B
— 0.33
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Q. What is the efficiency of a Carnot engine operating between temperatures of 500 K and 300 K?
A.
0.4
B.
0.5
C.
0.6
D.
0.7
Show solution
Solution
Efficiency (η) = 1 - (T2/T1) = 1 - (300/500) = 0.4 or 40%.
Correct Answer:
C
— 0.6
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Q. What is the final temperature when 200 g of ice at 0°C is added to 100 g of water at 80°C? (Specific heat of water = 4.2 J/g°C) (2020)
A.
0°C
B.
20°C
C.
40°C
D.
80°C
Show solution
Solution
Using the principle of conservation of energy, the heat lost by water equals the heat gained by ice. Solving gives a final temperature of 20°C.
Correct Answer:
B
— 20°C
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Q. What is the final temperature when 200 g of ice at 0°C is added to 100 g of water at 80°C? (Assume no heat loss to the surroundings) (2023)
A.
0°C
B.
20°C
C.
40°C
D.
80°C
Show solution
Solution
Using heat balance: m_ice * L_f + m_water * c * (T_final - 80) = 0. Solving gives T_final = 20°C.
Correct Answer:
B
— 20°C
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Q. What is the heat required to raise the temperature of 2 kg of aluminum from 25°C to 75°C? (Specific heat of aluminum = 0.9 J/g°C) (2022)
A.
9000 J
B.
18000 J
C.
36000 J
D.
4500 J
Show solution
Solution
Heat required Q = mcΔT = (2000 g)(0.9 J/g°C)(50°C) = 90000 J.
Correct Answer:
B
— 18000 J
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Q. What is the latent heat of fusion if 2000 J of energy is required to melt 0.5 kg of ice? (2021)
A.
2000 J/kg
B.
4000 J/kg
C.
1000 J/kg
D.
500 J/kg
Show solution
Solution
Latent heat of fusion (L) = Q / m = 2000 J / 0.5 kg = 4000 J/kg.
Correct Answer:
A
— 2000 J/kg
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Q. What is the latent heat of fusion if 2000 J of heat is required to melt 500 g of ice? (2022)
A.
2000 J/kg
B.
4000 J/kg
C.
1000 J/kg
D.
3000 J/kg
Show solution
Solution
Latent heat of fusion (L) = Q/m = 2000 J / 0.5 kg = 4000 J/kg.
Correct Answer:
A
— 2000 J/kg
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Q. What is the latent heat of fusion of ice if 80 calories are required to melt 20 grams of ice? (2020)
A.
40 cal/g
B.
60 cal/g
C.
80 cal/g
D.
100 cal/g
Show solution
Solution
Latent heat of fusion (L_f) = Q / m = 80 cal / 20 g = 4 cal/g.
Correct Answer:
C
— 80 cal/g
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Q. What is the latent heat of fusion of ice if 80 g of ice at 0°C melts to water at 0°C, absorbing 3360 J of heat? (2022)
A.
40 J/g
B.
60 J/g
C.
80 J/g
D.
100 J/g
Show solution
Solution
Latent heat of fusion (L) = Q/m = 3360 J / 80 g = 42 J/g.
Correct Answer:
C
— 80 J/g
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Q. What is the latent heat of vaporization if 500 g of water at 100°C is converted to steam at the same temperature, absorbing 2260 kJ of heat? (2023)
A.
2260 J/g
B.
450 J/g
C.
334 J/g
D.
1000 J/g
Show solution
Solution
Latent heat of vaporization (L) = Q / m = 2260 kJ / 500 g = 4.52 kJ/g = 2260 J/g.
Correct Answer:
A
— 2260 J/g
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Q. What is the latent heat of vaporization of water if 540 J of energy is required to convert 100 g of water at 100°C to steam? (2021)
A.
540 J/g
B.
54 J/g
C.
5.4 J/g
D.
0.54 J/g
Show solution
Solution
Latent heat of vaporization (L) = Q/m = 540 J / 100 g = 5.4 J/g.
Correct Answer:
A
— 540 J/g
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Q. What is the specific heat capacity of a substance if it requires 500 J to raise the temperature of 2 kg of the substance by 10°C? (2021)
A.
25 J/kg°C
B.
50 J/kg°C
C.
100 J/kg°C
D.
200 J/kg°C
Show solution
Solution
Specific heat capacity (c) = Q / (m * ΔT) = 500 J / (2 kg * 10°C) = 25 J/kg°C.
Correct Answer:
B
— 50 J/kg°C
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Q. What is the specific heat capacity of a substance if it requires 500 J to raise the temperature of 2 kg of the substance by 5°C? (2021)
A.
20 J/kg°C
B.
50 J/kg°C
C.
100 J/kg°C
D.
200 J/kg°C
Show solution
Solution
Specific heat capacity (c) = Q / (m * ΔT) = 500 J / (2 kg * 5°C) = 50 J/kg°C.
Correct Answer:
B
— 50 J/kg°C
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Q. What is the specific heat capacity of a substance if it takes 500 J to raise the temperature of 2 kg of the substance by 5°C? (2021)
A.
20 J/kg°C
B.
50 J/kg°C
C.
100 J/kg°C
D.
200 J/kg°C
Show solution
Solution
Specific heat capacity (c) = Q / (m * ΔT) = 500 J / (2 kg * 5°C) = 50 J/kg°C
Correct Answer:
B
— 50 J/kg°C
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Q. What is the specific heat capacity of water if it takes 4200 J to raise the temperature of 1 kg of water by 1°C? (2021)
A.
2100 J/kg°C
B.
4200 J/kg°C
C.
8400 J/kg°C
D.
1000 J/kg°C
Show solution
Solution
The specific heat capacity of water is defined as the amount of heat required to raise the temperature of 1 kg of water by 1°C, which is given as 4200 J/kg°C.
Correct Answer:
B
— 4200 J/kg°C
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Q. What is the temperature in Celsius if the temperature in Kelvin is 273 K?
A.
0°C
B.
100°C
C.
-273°C
D.
273°C
Show solution
Solution
To convert Kelvin to Celsius, use the formula: °C = K - 273. Therefore, 273 K - 273 = 0°C.
Correct Answer:
A
— 0°C
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Q. What is the temperature of a gas in Kelvin if its temperature in Celsius is 25°C? (2019)
A.
273 K
B.
298 K
C.
310 K
D.
325 K
Show solution
Solution
Temperature in Kelvin (K) = Temperature in Celsius (°C) + 273.15 = 25 + 273.15 = 298.15 K.
Correct Answer:
B
— 298 K
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Q. What is the thermal conductivity of a material if a 1 m² area of it conducts 100 J of heat in 10 seconds with a temperature difference of 20°C?
A.
2 W/m°C
B.
5 W/m°C
C.
10 W/m°C
D.
20 W/m°C
Show solution
Solution
Using the formula Q = kA(T1-T2)t, we find k = Q / (A(T1-T2)t) = 100 J / (1 m² * 20°C * 10 s) = 0.5 W/m°C.
Correct Answer:
B
— 5 W/m°C
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Q. What is the work done by an ideal gas during an isobaric expansion if it expands from 2 L to 5 L at a pressure of 3 atm? (2022)
A.
9 J
B.
12 J
C.
15 J
D.
18 J
Show solution
Solution
Work done (W) = P * ΔV = 3 atm * (5 L - 2 L) = 3 atm * 3 L = 9 atm·L = 15 J (1 atm·L = 101.325 J)
Correct Answer:
C
— 15 J
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Q. What is the work done by an ideal gas during an isobaric expansion if the pressure is 5 atm and the volume changes from 2 L to 5 L? (2019)
A.
15 L·atm
B.
10 L·atm
C.
5 L·atm
D.
20 L·atm
Show solution
Solution
Work done (W) = PΔV = P(V_final - V_initial) = 5 atm * (5 L - 2 L) = 15 L·atm.
Correct Answer:
A
— 15 L·atm
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Q. What is the work done on a gas when it is compressed from 4 L to 2 L at a constant pressure of 2 atm?
A.
4 L·atm
B.
2 L·atm
C.
8 L·atm
D.
0 L·atm
Show solution
Solution
Work done (W) = P * ΔV = 2 atm * (2 L - 4 L) = 2 atm * (-2 L) = -4 L·atm (work done on the gas is positive).
Correct Answer:
A
— 4 L·atm
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Q. What is the work done on a gas when it is compressed from 5 L to 2 L at a constant pressure of 200 kPa? (2022)
A.
600 J
B.
800 J
C.
1000 J
D.
1200 J
Show solution
Solution
Work done (W) = P * ΔV = 200 kPa * (2 L - 5 L) = 200 kPa * (-3 L) = -600 J (work done on the gas).
Correct Answer:
C
— 1000 J
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Q. What is the work done when 1 mole of an ideal gas expands isothermally from 10 L to 20 L at 300 K? (R = 8.31 J/mol·K) (2023)
A.
0 J
B.
830 J
C.
1660 J
D.
2490 J
Show solution
Solution
Work done = nRT ln(Vf/Vi) = 1 mol × 8.31 J/mol·K × 300 K × ln(20/10) = 1660 J.
Correct Answer:
C
— 1660 J
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Q. What is the work done when 1 mole of an ideal gas expands isothermally from 10 L to 20 L at a temperature of 300 K? (2020)
A.
1.5 kJ
B.
2.5 kJ
C.
3.5 kJ
D.
4.5 kJ
Show solution
Solution
Work done (W) = nRT ln(Vf/Vi) = 1 mol * 8.314 J/(mol K) * 300 K * ln(20/10) = 2.5 kJ.
Correct Answer:
B
— 2.5 kJ
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Q. What is the work done when 1 mole of an ideal gas expands isothermally from 10 L to 20 L at 300 K? (2022)
A.
300 J
B.
600 J
C.
150 J
D.
0 J
Show solution
Solution
Work done W = nRT ln(Vf/Vi) = 1 * 8.314 * 300 * ln(20/10) = 600 J.
Correct Answer:
B
— 600 J
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Showing 61 to 90 of 92 (4 Pages)
Heat & Thermodynamics MCQ & Objective Questions
Understanding Heat & Thermodynamics is crucial for students preparing for school and competitive exams in India. This topic not only forms a significant part of the syllabus but also helps in developing a strong foundation in physics. Practicing MCQs and objective questions on Heat & Thermodynamics can enhance your exam preparation, boost your confidence, and improve your chances of scoring better in important exams.
What You Will Practise Here
Fundamental concepts of heat, temperature, and thermodynamic laws.
Key formulas related to heat transfer, work done, and energy conservation.
Definitions of critical terms such as specific heat, latent heat, and thermal equilibrium.
Diagrams illustrating heat engines, refrigerators, and thermodynamic cycles.
Applications of the first and second laws of thermodynamics in real-world scenarios.
Problem-solving techniques for numerical questions related to heat and thermodynamics.
Common misconceptions and clarifications on heat-related phenomena.
Exam Relevance
Heat & Thermodynamics is a vital topic in various examinations, including CBSE, State Boards, NEET, and JEE. Students can expect questions that assess their understanding of concepts, application of formulas, and problem-solving abilities. Common question patterns include numerical problems, conceptual MCQs, and theoretical questions that require a clear grasp of the subject matter.
Common Mistakes Students Make
Confusing heat with temperature, leading to incorrect answers in conceptual questions.
Misapplying the laws of thermodynamics in numerical problems.
Overlooking units in calculations, which can result in significant errors.
Failing to interpret diagrams correctly, especially in heat engine-related questions.
FAQs
Question: What are the key formulas I should remember for Heat & Thermodynamics?Answer: Important formulas include Q = mcΔT for heat transfer, and W = PΔV for work done in thermodynamic processes.
Question: How can I improve my understanding of thermodynamic cycles?Answer: Practicing diagrams and solving related MCQs can significantly enhance your understanding of thermodynamic cycles.
Now is the time to take charge of your learning! Dive into our practice MCQs on Heat & Thermodynamics and test your understanding. Consistent practice will not only prepare you for exams but also solidify your grasp of essential concepts.
