AKTU Thermodynamics · Important Questions 2026Source: ryzenstudy.com PYQs
BME301 Thermodynamics Important Questions 2026 (AKTU)
Repeat analysis + most-asked questions, unit-wise
What we did: built from all 4 AKTU Thermodynamics papers (2021-22–2025-26): 88 questions grouped into 47 distinct questions, 23 of which were asked in more than one paper.
- of marks were repeat questions
- 56%
- of marks were repeat questions
- questions asked in 2+ papers
- 23
- questions asked in 2+ papers
- papers analysed (2021-22–2025-26)
- 4
- papers analysed (2021-22–2025-26)
- units, mapped to current syllabus
- 5
- units, mapped to current syllabus
How much of the paper repeats?
- Repeats are real: when we checked each newer BME301 paper against the papers before it, on average 56% of its marks were questions already asked in an earlier paper.
- 2023-24 paper: 41% of marks were repeats (7 of 10 repeated questions were in our top list).
- 2025-26 paper: 72% of marks were repeats (5 of 11 repeated questions were in our top list).
- Topic weightage is a guide, not a guarantee: our Tier 1 + Tier 2 topics covered 50% of the next paper's marks — picking the same number of topics at random would have covered about 48%.
Across 10 subjects and 23 papers we tested, 43% of marks repeated earlier questions on average.
1.Unit-wise most-asked questions
Ranked by how many papers asked them, then by how recently. Click a paper to open it.
Unit 1: Zeroth law of thermodynamics
16% of past marks| Question | Asked |
|---|---|
| Differentiate between macroscopic and microscopic viewpoints in thermodynamics | Asked 3× |
| Define thermodynamics and the concept of a thermodynamic system. Differentiate between open, closed, and isolated systems | Asked 2× |
| Define work and heat. Discuss the conventions used for sign assignment for both heat and work interactions. A gas is compressed from an initial state of 100 kPa and 0.01 m3 to a final state of 500 kPa and 0.002 m3. The process follows the path PV^1.2 = constant. Calculate the shaft work done if the process is carried out in a piston-cylinder device | Asked 2× |
| State the Zeroth Law of Thermodynamics | Asked 2× |
Unit 2:
19% of past marks| Question | Asked |
|---|---|
| 0.2 m3 of air at 4 bar and 130 °C is contained in a system. A reversible adiabatic expansion takes place till the pressure falls to 1.02 bar. The gas is then heated at constant pressure till enthalpy increases by 72.5 kJ. Calculate the work done. Take cp = 1 kJ/kg K, cv = 0.714 kJ/kg K | Asked 3× |
| Derive the steady flow energy equation and apply it to a compressor and turbine | Asked 2× |
| What is a PMM-I? Why is it impossible? | Asked 2× |
| Steam at 6.87 bar, 205 °C, enters an insulated nozzle with a velocity of 50 m/s. It leaves at a pressure of 1.37 bar and a velocity of 500 m/s. Determine the final enthalpy of steam | Asked 2× |
Unit 3: Entropy
28% of past marks| Question | Asked |
|---|---|
| 10 kg of water at 100 0C is mixed with 5 kg of water at 10 0C in an insulated tank. Calculate the total entropy change for the process. Take Cp = 4.18 kJ/kg K. Define Second Law Efficiency (II). Show that the Irreversibilit y(I) for a process is equal to the product of the reference temperature (T 0) and the Entropy Generation (Sgen) | Asked 4× |
| State the Kelvin-Planck and Clausius statements of the second law and establish their equivalence | Asked 3× |
| Write down the two fundamental TdS equations | Asked 2× |
| A heat engine is used to drive a heat pump. The heat transfers from the heat engine and from the heat pump are used to heat the water circulating through the radiators of (continues in next row, see original paper) | Asked 2× |
Unit 4:
18% of past marks| Question | Asked |
|---|---|
| Define Available Energy and Unavailable Energy | Asked 3× |
| Define the co-efficient of: (i) Volume expansion (ii) Isothermal compressibility (iii) Adiabatic compressibility | Asked 2× |
| Explain Helmholtz & Gibb’s function in detail. | Asked 2× |
| Explain Clausius-Clapeyron equation. Represent it on p-T diagram | Asked 2× |
Unit 5:
19% of past marks| Question | Asked |
|---|---|
| Define saturated states, sub-cooled liquid, and superheated vapor state | Asked 3× |
| Dryness fraction and its relation | Asked 2× |
| Explain triple point with diagram. | Asked 2× |
| A cyclic steam power plant is to be designed for a steam temperature at turbine inlet of 360 °C and an exhaust pressure of 0.08 bar. After isentropic expansion of steam in the turbine, the moisture content at the turbine exhaust is not to exceed 15%. Determine the greatest allowable steam pressure at the turbine inlet, and calculate the Rankine efficiency | Asked 2× |
2.Topic weightage: which topics carry the marks
Blue = Tier 1 + Tier 2 (topics that carried ~80% of past marks). Grey = the rest. It shows where marks have gone, not a promise of what comes next.
Triple, critical, saturation states · U5
10% (cum 10%)
Entropy change in processes · U3
9.2% (cum 19%)
First law for closed system · U2
8.4% (cum 28%)
Kelvin-Planck and Clausius statements · U3
6.6% (cum 34%)
Zeroth law and temperature scales · U1
4.9% (cum 39%)
Maxwell relations · U4
4.8% (cum 44%)
Simple Rankine cycle · U5
4.1% (cum 48%)
Steady flow energy equation · U2
3.8% (cum 52%)
Heat engine, heat pump, COP · U3
3.7% (cum 56%)
Macroscopic, microscopic, continuum · U1
3.6% (cum 59%)
Dryness fraction · U5
3.3% (cum 62%)
System and boundaries · U1
3.3% (cum 66%)
TdS equations, T-S diagram · U3
3.1% (cum 69%)
Steady flow devices · U2
3.1% (cum 72%)
Clapeyron equation · U4
2.9% (cum 75%)
Work and heat · U1
2.9% (cum 78%)
Available and unavailable energy · U4
2.6% (cum 80%)
Carnot cycle and theorem · U3
2.5% (cum 83%)
Internal energy and enthalpy · U2
2.2% (cum 85%)
Joule-Thomson coefficient · U4
2.2% (cum 87%)
Expansion and compressibility · U4
2% (cum 89%)
Reversibility and PMM-II · U3
2% (cum 91%)
Limits of first law, PMM-I · U2
1.9% (cum 93%)
Helmholtz and Gibbs functions · U4
1.7% (cum 95%)
Steam processes · U5
1.5% (cum 96%)
Availability and irreversibility · U4
1.3% (cum 98%)
State, property, process, cycle · U1
1.1% (cum 99%)
Second law efficiency · U4
1.1% (cum 100%)
Clausius inequality, entropy · U3
0.5% (cum 100%)
| Topic | Papers | Share |
|---|---|---|
| Triple, critical, saturation states · Unit 5 · Tier 1 | 4/4 | 10% |
| Entropy change in processes · Unit 3 · Tier 1 | 4/4 | 9.2% |
| First law for closed system · Unit 2 · Tier 1 | 3/4 | 8.4% |
| Kelvin-Planck and Clausius statements · Unit 3 · Tier 1 | 3/4 | 6.6% |
| Zeroth law and temperature scales · Unit 1 · Tier 1 | 3/4 | 4.9% |
| Maxwell relations · Unit 4 · Tier 1 | 1/4 | 4.8% |
| Simple Rankine cycle · Unit 5 · Tier 1 | 3/4 | 4.1% |
| Steady flow energy equation · Unit 2 · Tier 1 | 2/4 | 3.8% |
| Heat engine, heat pump, COP · Unit 3 · Tier 2 | 2/4 | 3.7% |
| Macroscopic, microscopic, continuum · Unit 1 · Tier 2 | 4/4 | 3.6% |
| Dryness fraction · Unit 5 · Tier 2 | 2/4 | 3.3% |
| System and boundaries · Unit 1 · Tier 2 | 2/4 | 3.3% |
| TdS equations, T-S diagram · Unit 3 · Tier 2 | 2/4 | 3.1% |
| Steady flow devices · Unit 2 · Tier 2 | 2/4 | 3.1% |
| Clapeyron equation · Unit 4 · Tier 2 | 2/4 | 2.9% |
| Work and heat · Unit 1 · Tier 2 | 2/4 | 2.9% |
| Available and unavailable energy · Unit 4 · Tier 2 | 3/4 | 2.6% |
| Carnot cycle and theorem · Unit 3 · Tier 3 | 2/4 | 2.5% |
| Internal energy and enthalpy · Unit 2 · Tier 3 | 1/4 | 2.2% |
| Joule-Thomson coefficient · Unit 4 · Tier 3 | 2/4 | 2.2% |
| Expansion and compressibility · Unit 4 · Tier 3 | 2/4 | 2% |
| Reversibility and PMM-II · Unit 3 · Tier 3 | 2/4 | 2% |
| Limits of first law, PMM-I · Unit 2 · Tier 3 | 2/4 | 1.9% |
| Helmholtz and Gibbs functions · Unit 4 · Tier 3 | 2/4 | 1.7% |
| Steam processes · Unit 5 · Tier 3 | 1/4 | 1.5% |
| Availability and irreversibility · Unit 4 · Tier 3 | 1/4 | 1.3% |
| State, property, process, cycle · Unit 1 · Tier 3 | 2/4 | 1.1% |
| Second law efficiency · Unit 4 · Tier 3 | 2/4 | 1.1% |
| Clausius inequality, entropy · Unit 3 · Tier 3 | 1/4 | 0.5% |
3.Paper pattern (2025-26)
| Section | Questions | Rule |
|---|---|---|
| A | 6 × 2 marks | Attempt all |
| B | 5 × 7 marks | Attempt any 3 |
| C | 4 × 7 marks | Attempt any 1 |
4.In the syllabus, never asked yet
Low priority, but read them once — a new paper can always start here.
- Gas laws and ideal gas · U1
- Unsteady processes · U2
- Pure substance phases · U5
- Property diagrams · U5
- Steam tables, Mollier chart · U5
5.Study order
- 1Triple, critical, saturation states (Unit 5, Tier 1)
- 2Entropy change in processes (Unit 3, Tier 1)
- 3First law for closed system (Unit 2, Tier 1)
- 4Kelvin-Planck and Clausius statements (Unit 3, Tier 1)
- 5Zeroth law and temperature scales (Unit 1, Tier 1)
- 6Maxwell relations (Unit 4, Tier 1)
- 7Simple Rankine cycle (Unit 5, Tier 1)
- 8Steady flow energy equation (Unit 2, Tier 1)
- 9Heat engine, heat pump, COP (Unit 3, Tier 2)
- 10Macroscopic, microscopic, continuum (Unit 1, Tier 2)
- 11Dryness fraction (Unit 5, Tier 2)
- 12System and boundaries (Unit 1, Tier 2)
- 13TdS equations, T-S diagram (Unit 3, Tier 2)
- 14Steady flow devices (Unit 2, Tier 2)
- 15Clapeyron equation (Unit 4, Tier 2)
- 16Work and heat (Unit 1, Tier 2)
- 17Available and unavailable energy (Unit 4, Tier 2)
FAQ
Which units of BME301 carry the most marks?
Unit 3 (Entropy, 28% of past marks) and Unit 2 (, 19% of past marks).
Do AKTU Thermodynamics questions repeat?
Yes. On average 56% of the marks in each newer BME301 paper came from questions already asked in an earlier paper, and 23 questions have appeared in more than one paper.
How is this list made?
Every question from the 4 papers (2021-22–2025-26) was mapped to the current AKTU syllabus and grouped with the same question from other years. Questions are ranked by how many papers they appeared in, then by how recently.
Study this subject
Note: this is based on past AKTU papers, not a guarantee. Questions are mapped to the current syllabus; topics that are no longer in the syllabus are left out.