Phase Behaviour and Equations of State - Properties of Pure Substances - Engineering Sciences Previous Year Questions

1

2007 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2007

The specific gravity of ice at 0°C is

A

greater than unity

B

less than unity

C

equal to unity

D

cannot say; insufficient information

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2

2007 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2007

Which one of the following equations is correct?

A

\(v = (1-x)v_f + x v_g\)

B

\(v = v_f + v_g\)

C

\(v = x v_f + (1-x)v_g\)

D

\(v = x(v_f + v_g)\)

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3

2007 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2007

Two systems A and B, possessing the same internal energy, contain saturated liquid-vapour mixture of water at 1 MPa. The maximum value of the ratio of their masses is

A

1.4

B

2.4

C

3.4

D

4.4

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4

2007 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2007

A rigid vessel contains saturated liquid-vapour mixture of water at 10 MPa. On being heated, the mixture reaches the critical point. The initial quality of the mixture is approximately

A

1 %

B

5 %

C

10 %

D

15 %

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5

2007 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2007

Match items in Group I with those in Group II

A

P-1, Q-2, R-3

B

P-1, Q-3, R-2

C

P-2, Q-1, R-3

D

P-2, Q-1, R-4

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6

2008 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2008

At constant temperature, pressure of an incompressible fluid is changed from 400 kPa to 4 MPa. Which of the following set of thermodynamic properties remain unchanged during the process?
(\( u \) is specific internal energy, \( v \) is specific volume, \( h \) is specific enthalpy and \( s \) is specific entropy)

A

\(u, v, h \)

B

\(u, s, h \)

C

\(u, v, s \)

D

\(v, s, h \)

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7

2008 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2008

Steam of quality 0.98 is present in two separate containers A and B at 300 kPa and 200 kPa, respectively. Specific volumes of steam in containers A and B initially are \(v_{s1}\) and \(v_{s2}\), respectively. Steam condenses at a constant pressure in such a way that the final quality of steam in both the containers is 0.01 and specific volumes of steam in containers A and B are \(v_{s2}\) and \(v_{s2}\), respectively. Which one of the following statements is true?

A

\(v_{s1} > v_{s1}\) & \(v_{s2} > v_{s2}\)

B

\(v_{s1} < v_{s1}\) & \(v_{s2} < v_{s2}\)

C

\(v_{s1} > v_{s1}\) & \(v_{s2} < v_{s2}\)

D

\(v_{s1} < v_{s1}\) & \(v_{s2} > v_{s2}\)

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8

2008 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2008

For a refrigerant, the slope \(\left(\frac{dP}{dT}\right)_{sat}\) of the saturation curve on a P-T diagram is a function of the temperature, the enthalpy of vaporization and the difference between specific volumes of the saturated liquid and saturated vapor. If at 20 °C, for the refrigerant, \(\left(\frac{dP}{dT}\right)_{sat} = 17.69\) kPa/K, \(v_f = 0.0008157\) m³/kg and \(v_g = 0.0358\) m³/kg, the enthalpy of vaporization in kJ/kg at 20 °C is approximately:

A

12.38

B

273.77

C

353.8

D

181.5

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9

2009 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2009

The ideal gas law is valid for

A

inert gases

B

gases at high pressure and high temperature

C

gases at low pressure and low temperature

D

gases at low pressure and high temperature

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10

2009 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2009

An ideal gas undergoes expansion according to the process \( PV^{0.5} = \) constant. The temperature of the gas during the expansion process

A

does not change

B

increases

C

decreases

D

changes depending on the initial condition

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11

2009 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2009

The saturation pressures of water at 100 °C and 105 °C are respectively 101.3 kPa and 120.8 kPa. Taking the molecular weight of water as 18, the latent heat of water in kJ/kg at 102.5 °C is approximately equal to

A

2290

B

1250

C

820

D

330

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12

2009 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2009

On a T-s diagram, the slope of the constant volume line for an ideal gas is

A

less than that of constant pressure line

B

more than that of constant pressure line

C

less than that of constant enthalpy line

D

equal to that of constant enthalpy line

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13

2009 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2009

A pressure cooker contains saturated water-vapour mixture at 100 °C with volume of vapour being eight times that of the volume of liquid. The specific volume of saturated liquid and saturated vapour at 100 °C are, $v_f = 0.001044$ m³/kg and $v_g = 1.6729$ m³/kg, respectively. The quality of the mixture is

A

0.005

B

0.125

C

0.889

D

0.995

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14

2010 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2010

1 kg of methane is enclosed in a cylinder having volume 6.4 litres and is maintained at a temperature of 13°C and pressure of 18.56 MPa. If molecular weight of methane is 16 kg/kmol (for methane, critical pressure = 4.64 MPa, critical temperature is 191.1 K; universal gas constant is 8.314 kJ/kmol-K), compressibility factor, Z, is

A

0.375

B

0.8

C

1.25

D

2.66

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15

2011 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2011

At a certain pressure, the specific volumes (m³/kg) of saturated liquid, saturated vapor, and wet steam are 1.1565 × 10^-3, 0.1274, and 0.1, respectively. The quality of wet steam is

A

0.805

B

0.783

C

0.776

D

0.673

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16

2011 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2011

Specific heat at constant pressure (C_p) of helium is 5.19 kJ/kg.K and its molecular mass is 4 kg/kmol. The specific heat at constant volume of helium, in kJ/kg.K, is

A

1.11

B

2.11

C

3.11

D

4.11

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17

2011 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2011

Given for water,
at 190°C, saturation pressure = 12.54 bar
at 210°C, saturation pressure = 19.06 bar
at 200°C, specific volume of saturated liquid = \(1.1565 \times 10^{-3}\) m³/kg
at 200°C, specific volume of saturated vapor = 0.1274 m³/kg
Using Clapeyron equation, the enthalpy of vaporization (kJ/kg) of water at 200°C is approximately

A

1857

B

1924

C

1947

D

2025

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18

2012 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2012

In each of the following choices, there are two expressions given. Select the choice that gives, first, the defining expression of volume expansivity and second, the expression of volume expansivity for ideal gases

A

\(\frac{1}{v}\left(\frac{\partial v}{\partial T}\right)_P \), \(\frac{1}{T} \)

B

\(\frac{1}{v}\left(\frac{\partial v}{\partial P}\right)_T \), \(\frac{1}{T} \)

C

\(-\frac{1}{v}\left(\frac{\partial v}{\partial P}\right)_T \), \(\frac{1}{P} \)

D

\(\frac{1}{v}\left(\frac{\partial v}{\partial T}\right)_P \), \(\frac{1}{P} \)

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19

2012 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2012

The temperature and pressure at the triple point are

A

295.2 K, 0.69 atm

B

295.2 K, 0.59 atm

C

195.2 K, 0.69 atm

D

195.2 K, 0.59 atm

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20

2012 · Engineering Sciences · Properties of Pure Substances · Phase Behaviour and Equations of State

Engineering Sciences (XE) 2012

The latent heat of vaporization is

A

1298 kJ/kg

B

1398 kJ/kg

C

1498 kJ/kg

D

1698 kJ/kg

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