MCQOPTIONS
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MCQOPTIONS
This section includes 25 Mcqs, each offering curated multiple-choice questions to sharpen your Thermodynamics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Compressed air coming out from a punctured football _____. |
| A. | Becomes hotter |
| B. | Becomes cooler |
| C. | Remains at the same temperature |
| D. | May become hotter or cooler depending upon the humidity of the surrounding air |
| Answer» C. Remains at the same temperature | |
| 2. |
A reversible adiabatic in a T-S diagram is a ________. |
| A. | point |
| B. | vertical line |
| C. | horizontal line |
| D. | parabolic curve |
| Answer» C. horizontal line | |
| 3. |
During melting, the volume of a pure substance other than water: |
| A. | Decreases |
| B. | Increases |
| C. | Remains constant |
| D. | First increases and then decrease |
| Answer» C. Remains constant | |
| 4. |
Pick the correct statement about pure substance. |
| A. | A mixture of liquid air and gaseous air is a pure substance. |
| B. | A mixture of ice and liquid water is not a pure substance. |
| C. | A mixture of two or more phases of pure substance is not a pure substance even though the chemical composition of all the phases is the same throughout |
| D. | A mixture of two or more phases of pure substance is still a pure substance as long as the chemical composition of all the phases is the same throughout |
| Answer» E. | |
| 5. |
Joule-Thomson coefficient is defined as |
| A. | \({\left( {\frac{{\partial T}}{{\partial p}}} \right)_h}\) |
| B. | \({\left( {\frac{{\partial h}}{{\partial p}}} \right)_T}\) |
| C. | \({\left( {\frac{{\partial h}}{{\partial T}}} \right)_P}\) |
| D. | \({\left( {\frac{{\partial p}}{{\partial T}}} \right)_h}\) |
| Answer» B. \({\left( {\frac{{\partial h}}{{\partial p}}} \right)_T}\) | |
| 6. |
A gas having a negative Joule-Thomson coefficient (μ < 0), when throttled, will |
| A. | Become cooler |
| B. | Become warmer |
| C. | First become cooler and then warmer |
| D. | Either be cooler or warmer depending on the type of gas |
| Answer» C. First become cooler and then warmer | |
| 7. |
A substance which has a fixed chemical composition throughout is called a: |
| A. | solid substance |
| B. | hard substance |
| C. | pure substance |
| D. | soft substance |
| Answer» D. soft substance | |
| 8. |
At triple point for water, which of the following term is not equal to zero? |
| A. | Enthalpy |
| B. | Entropy |
| C. | Internal energy |
| D. | None of these |
| Answer» B. Entropy | |
| 9. |
Along the ‘triple line’ in a p – v diagram showing all three phase of water, which one of the following statements is correct? |
| A. | A substance has the same pressure and temperature but different specific volume |
| B. | A substance has same temperature and specific volume but different pressure |
| C. | A substance has same specific volume and pressure but different temperature |
| D. | A substance has same specific volume pressure and temperature. |
| Answer» B. A substance has same temperature and specific volume but different pressure | |
| 10. |
Joule - Thomson coefficient is given by: |
| A. | \({\left( {\frac{{\partial p}}{{\partial T}}} \right)_h}\) |
| B. | \({\left( {\frac{{\partial T}}{{\partial h}}} \right)_p}\) |
| C. | \({\left( {\frac{{\partial h}}{{\partial p}}} \right)_T}\) |
| D. | \({\left( {\frac{{\partial T}}{{\partial p}}} \right)_h}\) |
| Answer» E. | |
| 11. |
For an ideal gas with constant values of specific heats, for calculation of the specific enthalpy, |
| A. | it is sufficient to know only the temperature |
| B. | both temperature and pressure are required to be known |
| C. | both temperature and volume are required to be known |
| D. | both temperature and mass are required to be known |
| Answer» B. both temperature and pressure are required to be known | |
| 12. |
In a P-V diagram for pure substance, the constant temperature line in superheated region is ________. |
| A. | converging |
| B. | diverging |
| C. | intersecting |
| D. | parallel |
| Answer» C. intersecting | |
| 13. |
Define pure substance. |
| A. | A single substance without any mixture |
| B. | Substance which is available in the purest form in nature |
| C. | Substance with non-uniform composition |
| D. | Substance with fixed chemical composition throughout |
| Answer» E. | |
| 14. |
If x represents the dryness fraction of steam, the specific volume of wet steam is given by |
| A. | x2vf |
| B. | xvf |
| C. | x2vg |
| D. | xvg |
| Answer» E. | |
| 15. |
Given below an extract from steam tables. The specific enthalpy of water in kJ/kg at 150 bar and 45 °C will be Specific Volume (m3/kg)Enthalpy (KJ/kg)Temperature(° C)P saturated (bar)Saturated liquidSaturated vapourSaturated liquidSaturated vapour450.095930.00101015.26188.452394.8342.241500.0016580.103371610.52610.5 |
| A. | 203.6 |
| B. | 200.53 |
| C. | 196.38 |
| D. | 188.45 |
| Answer» E. | |
| 16. |
If a pure substance is below the triple point temperature, the solid on being heated will only |
| A. | solidify or freeze |
| B. | liquefy |
| C. | vaporize or sublimate |
| D. | have its temperature increased |
| Answer» D. have its temperature increased | |
| 17. |
At which pressure (in kg/cm2) the properties of water and steam become identical |
| A. | 0.1 |
| B. | 1 |
| C. | 100 |
| D. | 221.2 |
| Answer» E. | |
| 18. |
A vessel of volume 0.04 m3 contains a mixture of saturated water and steam at 200°C. The mass of liquid is 5 kg. Find the mass of vapor in the mixture (given vf = 0.0011 and vg = 0.12 m3/kg at 200°C). |
| A. | 0.29 kg |
| B. | 0.78 kg |
| C. | 2.1 kg |
| D. | 450 gm |
| Answer» B. 0.78 kg | |
| 19. |
A vessel has two compartments. First compartment contains 2 kg of dry saturated steam at 7 bar [v[email protected] = 0.27 m3/kg] and second compartment contains 1 kg of steam of dryness fraction of 0.8 at 3.5 bar [v[email protected] 3.5 bar = 0.55 m3/kg]. After the partition is removed, the pressure of the mixture is found to be 5 bar [v[email protected] bar = 0.37 m3/kg]. Neglecting the volume of water, what will be the specific volume of mixture? |
| A. | 0.281 m3/kg |
| B. | 0.326 m3/kg |
| C. | 0.462 m3/kg |
| D. | 0.521 m3/kg |
| Answer» C. 0.462 m3/kg | |
| 20. |
One kg of steam sample contains 0.8 kg dry steam; it’s dryness fraction is |
| A. | 0.2 |
| B. | 0.8 |
| C. | 0.6 |
| D. | 0.5 |
| Answer» C. 0.6 | |
| 21. |
In the Mollier diagram, the isotherm in the superheated region at low pressures becomes ________. |
| A. | diverge from one another |
| B. | horizontal |
| C. | parallel |
| D. | vertical |
| Answer» C. parallel | |
| 22. |
Addition of heat at constant pressure to a gas results in ________. |
| A. | Raising its temperature |
| B. | Raising its pressure |
| C. | Raising its volume |
| D. | Raising its temperature and doing external work |
| Answer» E. | |
| 23. |
Fusion curve on P-T diagram for all substances possesses the following slope |
| A. | zero |
| B. | infinity |
| C. | positive |
| D. | variable |
| Answer» E. | |
| 24. |
In a P-T diagram for pure substance, the melting line has highest inclination with respect to the positive horizontal axis representing temperature for which type of substance? |
| A. | Substance that contracts on freezing. |
| B. | Substance that expands on freezing. |
| C. | Substance that has same volume on freezing. |
| D. | None of these |
| Answer» C. Substance that has same volume on freezing. | |
| 25. |
In a P-T phase diagram of a pure substance, which of the following lines separates solid and liquid region? |
| A. | Sublimation lines |
| B. | Vaporization line |
| C. | Fusion line |
| D. | Triple point |
| Answer» D. Triple point | |