MCQOPTIONS
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MCQOPTIONS
This section includes 24 Mcqs, each offering curated multiple-choice questions to sharpen your Thermodynamics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
If value of dryness fraction is 0, indicates that working fluid is at ______. |
| A. | Saturated Liquid |
| B. | Saturated Vapour |
| C. | Superheated Vapour |
| D. | Compressed Liquid |
| Answer» B. Saturated Vapour | |
| 2. |
On a Mollier chart, the constant pressure lines |
| A. | Diverge from left to right |
| B. | Diverge from right to left |
| C. | Are equispaced throughout |
| D. | First rise up and then fall |
| Answer» B. Diverge from right to left | |
| 3. |
Mollier chart is drawn between |
| A. | temperature and pressure |
| B. | temperature and entropy |
| C. | enthalpy and entropy |
| D. | pressure and enthalpy |
| Answer» D. pressure and enthalpy | |
| 4. |
Calculate the dryness fraction of steam which has 1.5 kg of water in suspension with 50 kg of steam. |
| A. | 0.83 |
| B. | 0.97 |
| C. | 0.68 |
| D. | 0.75 |
| Answer» C. 0.68 | |
| 5. |
A mass of wet steam contains 15% liquid water. The dryness fraction of steam is |
| A. | 0.15 |
| B. | 0.85 |
| C. | 1.15 |
| D. | None of these |
| Answer» C. 1.15 | |
| 6. |
If any substance is cooled below its triple point pressure, vapour becomes solid and the process is known as: |
| A. | sublimation |
| B. | vaporisation |
| C. | ablimation |
| D. | saturation |
| Answer» D. saturation | |
| 7. |
A liquid that boils at a relatively high temperature is said to have |
| A. | a low viscosity |
| B. | a high viscosity |
| C. | a high volatility |
| D. | a low volatility |
| Answer» E. | |
| 8. |
Mass of vapor in 1 kg of wet steam of dryness fraction 0.95 is |
| A. | 950 g |
| B. | 1.95 kg |
| C. | 50 g |
| D. | None of the above |
| Answer» B. 1.95 kg | |
| 9. |
A rigid container of volume 0.5 m3 contains 1.0 kg of water at 120°C (vf = 0.00106 m3/kg, vg = 0.8908 m3/kg). The state of water is |
| A. | Compressed liquid |
| B. | Saturated liquid |
| C. | A mixture of saturated liquid and saturated vapor |
| D. | Superheated vapor |
| Answer» D. Superheated vapor | |
| 10. |
If a1 and a2 are the dryness fractions obtained in separating calorimeter and throttling calorimeter respectively, then the actual dryness fraction of steam will be: |
| A. | a1a2 |
| B. | (a1 + a2)/2 |
| C. | a1 + a2 |
| D. | (a1a2)/2 |
| Answer» B. (a1 + a2)/2 | |
| 11. |
For dry saturated vapour, the value of dryness fraction will be |
| A. | 1 |
| B. | 0.75 |
| C. | 0.5 |
| D. | 0 |
| Answer» B. 0.75 | |
| 12. |
If the dryness fraction of a sample by throttling calorimeter is 0.8 and that by separating calorimeter is also 0.8, then the actual dryness fraction of sample will be taken as |
| A. | 0.8 |
| B. | \(\sqrt {0.8}\) |
| C. | 0.64 |
| D. | 0.5 |
| Answer» D. 0.5 | |
| 13. |
If 1 kg mixture of steam contains 0.8 kg of dry vapor and 0.2 kg of moisture, then the dryness fraction of the steam is |
| A. | 0.8 |
| B. | 0.6 |
| C. | 0.2 |
| D. | 0.5 |
| Answer» B. 0.6 | |
| 14. |
In an experiment to determine dryness fraction of steam, the mass of water separated was 1.2 kg in 15 minutes and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is: |
| A. | 40% |
| B. | 25% |
| C. | 50% |
| D. | 80% |
| Answer» E. | |
| 15. |
In 1 kg of wet steam, dry steam is 0.9 kg and water particles is 0.1 kg. What is the dryness fraction? |
| A. | 0.9 |
| B. | 1 |
| C. | 9 |
| D. | 0.1 |
| Answer» B. 1 | |
| 16. |
If y is the weight of dry steam and x is the weight of water suspension, then dryness fraction is equal to |
| A. | \(\frac{x}{y +x}\) |
| B. | \(\frac{y}{x +y}\) |
| C. | \(\frac yx\) |
| D. | \(\frac xy\) |
| Answer» C. \(\frac yx\) | |
| 17. |
A closed vessel contains pure water, in thermal equilibrium with its vapour at 25°C (Stage #1), as shown.The vessel in this stage is then kept inside an isothermal oven which is having an atmosphere of hot air maintained at 80°C. The vessel exchanges heat with the oven atmosphere and attains a new thermal equilibrium (Stage #2). If the Valve A is now opened inside the oven, what will happen immediately after opening the valve? |
| A. | Water vapour inside the vessel will come out of the Valve A |
| B. | Hot air will go inside the vessel through Valve A |
| C. | Nothing will happen – the vessel will continue to remain in equilibrium |
| D. | All the vapour inside the vessel will immediately condense |
| Answer» C. Nothing will happen – the vessel will continue to remain in equilibrium | |
| 18. |
In a non – flow process, work transfer from the system is 30 kJ, and heat received by the system is 90 kJ. Determine the change in the internal energy. |
| A. | -60 kJ |
| B. | -80 kJ |
| C. | 60 kJ |
| D. | 80 kJ |
| Answer» D. 80 kJ | |
| 19. |
Heating of dry steam above saturation temperature is known as |
| A. | Superheating |
| B. | Supersaturation |
| C. | Super tempering |
| D. | Saturation heating |
| Answer» B. Supersaturation | |
| 20. |
Consider the following statements:1. There is no change in temperature when a liquid is being evaporated into vapour2. Vapour is a mixed phase of liquid and gas in the zone between saturated liquid line and saturated vapour line3. The saturated dry vapour curve is steeper as compared to saturated liquid curve on a T-s diagram4. The enthalpy of vaporization decreases with increase in pressureWhich of the above statements are correct? |
| A. | 1, 2 and 3 only |
| B. | 3 and 4 only |
| C. | 1, 2 and 4 only |
| D. | 1, 2, 3 and 4 |
| Answer» D. 1, 2, 3 and 4 | |
| 21. |
A positive value of Joule-Thomson coefficient of a fluid means |
| A. | Temperature drops during throttling |
| B. | Temperature remains constant during throttling |
| C. | Temperature rises during throttling |
| D. | None of the these |
| Answer» B. Temperature remains constant during throttling | |
| 22. |
A vapour which is about to condense is called |
| A. | sub-cooled vapour |
| B. | saturated vapour |
| C. | superheated vapour |
| D. | cold vapour |
| Answer» C. superheated vapour | |
| 23. |
One kg of steam sample contains 0.4 kg dry steam, it’s dryness fraction is |
| A. | 0.4 |
| B. | 0.6 |
| C. | 4/14 |
| D. | 0.4 × 0.6 |
| Answer» B. 0.6 | |
| 24. |
For a simple compressible system, v, s, p and T are specific volume, specific entropy, pressure and temperature, respectively. As per Maxwell’s relations, \({\left( {\frac{{\partial v}}{{\partial s}}} \right)_p}\) is equal to |
| A. | \({\left( {\frac{{\partial s}}{{\partial T}}} \right)_p}\) |
| B. | \({\left( {\frac{{\partial p}}{{\partial v}}} \right)_T}\) |
| C. | \( - {\left( {\frac{{\partial T}}{{\partial v}}} \right)_p}\) |
| D. | \({\left( {\frac{{\partial T}}{{\partial p}}} \right)_s}\) |
| Answer» E. | |