# Thermodynamics Questions and Answers – Quality or Dryness Fraction and Charts of Thermodynamics Properties

This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “Quality or Dryness Fraction and Charts of Thermodynamics Properties”.

1. Quality indicates the
a) mass fraction of liquid in a liquid vapour mixture
b) mass fraction of vapour in a liquid vapour mixture
c) both of the mentioned
d) none of the mentioned

Explanation: Quality, x is given as mass of vapour divided by the total mass of liquid-vapour mixture.

2. If 1 kg of liquid-vapour mixture is considered and x is the quality of that mixture, then
a) mass of vapour is x kg
b) mass of liquid is (1-x) kg
c) both of the mentioned
d) none of the mentioned

Explanation: Quality indicates the mass fraction of vapour in a liquid vapour mixture.

3. Which of the following statements is true?
a) the value of x varies between 0 and 1
b) for saturated water, x=0
c) for saturated vapour, x=1
d) all of the mentioned

Explanation: When water just starts boiling, x=0 and when vaporization is complete, x=1.

4. Total volume of a liquid vapour mixture is given by
a) volume of the saturated liquid
b) volume of the saturated vapour
c) sum of volumes of saturated liquid and saturated vapour
d) none of the mentioned

Explanation: V=Vf+Vg.

5. Voidage is given by
a) specific volume of saturated vapour / specific volume of liquid vapour mixture
b) specific volume of liquid vapour mixture / specific volume of saturated vapour
c) specific volume of saturated liquid / specific volume of liquid vapour mixture
d) specific volume of liquid vapour mixture / specific volume of saturated liquid

Explanation: Voidage is the volume fraction of vapour.

6. Specific volume of the mixture is given by
a) (1+x)vf + (x)vg
b) (1-x)vf + (x)vg
c) (1-x)vf – (x)vg
d) none of the mentioned

Explanation: Here vf=specific volume of saturated solid and vg=specific volume of saturated vapour.

7. Which of the following is correct?
a) v=vf + (x*vfg)
b) h=hf + (x*hfg)
c) s=sf + (x*sfg)
d) all of the mentioned

Explanation: Here, fg for each property is f-g for each property.

8. Which of the following statement is true about a chart of thermodynamic property?
a) the manner of variation of properties is clearly given in a chart
b) there is no problem in interpolation
c) the precision is not as much as in steam tables
d) all of the mentioned

9. The temperature-entropy plot and enthalpy-entropy plot are commonly used.
a) true
b) false

Explanation: But its scale is small and limited in use.

10. Which of the following statement is true?
a) the temperature-entropy plot shows the vapour dome and the lines of constant volume, constant pressure, constant enthalpy, constant entropy and constant superheat
b) the scale of temperature-entropy plot is small which limits its use
c) enthalpy-entropy plot has a larger scale to provide data suitable for many computations
d) all of the mentioned