Thermodynamics Practice Questions
HSC/SSC (Bangladesh) · HSC Physics · 151 free MCQs with instant results and detailed explanations.
151
Total
56
Easy
72
Medium
23
Hard
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Sample Questions from Thermodynamics
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Q1
Easy
What is the primary principle of the first law of thermodynamics?
A.
Energy cannot be created or destroyed.
B.
Heat flows from cold to hot spontaneously.
C.
All temperatures are absolute.
D.
Work can be converted into mass.
Show Answer & Explanation
Correct Answer: A
The first law of thermodynamics states that energy cannot be created or destroyed, only transformed from one form to another. This principle underlies all thermodynamic processes.
Q2
Easy
If 500 J of heat energy is added to a system and 200 J of work is done by the system, what is the change in internal energy?
A.
300 J
B.
700 J
C.
200 J
D.
500 J
Show Answer & Explanation
Correct Answer: A
According to the first law of thermodynamics, the change in internal energy (ฮU) is given by ฮU = Q - W. Here, Q = 500 J and W = 200 J, so ฮU = 500 J - 200 J = 300 J.
Q3
Easy
Which of the following statements about thermal equilibrium is true?
A.
Heat flows between two systems in thermal equilibrium.
B.
Two systems at thermal equilibrium have the same temperature.
C.
Thermal equilibrium can occur at any temperature difference.
D.
All materials reach thermal equilibrium at the same rate.
Show Answer & Explanation
Correct Answer: B
Thermal equilibrium occurs when two systems are at the same temperature, meaning no net heat flows between them. This is the key characteristic of thermal equilibrium.
Q4
Medium
During a process, 200 J of heat is added to a system and does 150 J of work. What is the change in internal energy of the system?
A.
50 J
B.
350 J
C.
150 J
D.
0 J
Show Answer & Explanation
Correct Answer: A
According to the first law of thermodynamics, ฮU = Q - W. Here, Q = 200 J and W = 150 J, so ฮU = 200 J - 150 J = 50 J.
Q5
Medium
Which of the following statements about entropy is true?
A.
Entropy can never decrease in an isolated system.
B.
Entropy is a measure of energy available for doing work.
C.
Entropy is always zero at absolute zero temperature.
D.
Entropy increases only in reversible processes.
Show Answer & Explanation
Correct Answer: A
In an isolated system, the total entropy can never decrease; it either stays the same or increases, which is a fundamental principle of the second law of thermodynamics.
Q6
Medium
A gas expands isothermally at 300 K and absorbs 500 J of heat. What is the work done by the gas if the internal energy remains constant?
A.
500 J
B.
0 J
C.
-500 J
D.
250 J
Show Answer & Explanation
Correct Answer: A
In an isothermal process for an ideal gas, the change in internal energy (ฮU) is zero. Therefore, from the first law, Q = W. Since Q = 500 J, the work done (W) is also 500 J.
Q7
Medium
In an ideal gas, which of the following conditions will lead to an increase in pressure, assuming volume is constant?
A.
Decreasing the number of gas molecules
B.
Increasing the temperature of the gas
C.
Increasing the volume of the gas
D.
Decreasing the temperature of the gas
Show Answer & Explanation
Correct Answer: B
According to Gay-Lussac's law, pressure increases with temperature if volume is constant, as the gas particles move faster, colliding with walls more frequently.
Q8
Hard
In a closed system, 500 J of heat is added to a gas, which does 200 J of work on its surroundings. What is the change in internal energy of the gas?
A.
300 J
B.
700 J
C.
200 J
D.
500 J
Show Answer & Explanation
Correct Answer: A
According to the first law of thermodynamics, the change in internal energy (ฮU) is equal to the heat added to the system (Q) minus the work done by the system (W). Here, ฮU = Q - W = 500 J - 200 J = 300 J.
Q9
Hard
A cylinder with a movable piston contains 2 moles of an ideal gas at 27ยฐC. If the volume of the gas is doubled isothermally, what will be the final pressure if the initial pressure is 3 atm?
A.
1.5 atm
B.
3 atm
C.
6 atm
D.
0.75 atm
Show Answer & Explanation
Correct Answer: A
For an isothermal process involving an ideal gas, the relationship between pressure and volume is given by Boyle's Law (P1V1 = P2V2). If the volume is doubled (V2 = 2V1), the pressure will be halved. Thus, P2 = P1/2 = 3 atm / 2 = 1.5 atm.
Q10
Hard
Two identical containers have gases at the same temperature, but one container has double the pressure of the other. What can be concluded about the gas density in the two containers?
A.
The denser container has twice the density.
B.
The density of both containers is the same.
C.
The denser container has half the density.
D.
The denser container has four times the density.
Show Answer & Explanation
Correct Answer: A
According to the ideal gas law (PV = nRT), if pressure is doubled while temperature remains constant, density must also double because density (ฯ) is proportional to pressure (P) for a given temperature (T). Thus, the container with double the pressure must have twice the density.
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Thermodynamics โ HSC/SSC (Bangladesh) HSC Physics Practice Questions Online
This page contains 151 practice MCQs for the chapter Thermodynamics in HSC/SSC (Bangladesh) HSC Physics. The questions are organized by difficulty โ 56 easy, 72 medium, 23 hard โ so you can choose the right level for your preparation.
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