Deck 14: Thermodynamics and Properties of Substances

Question 1

A chip dissipates 2 kJ of electric work and rejects it as heat transfer from its surface which is at 50°C to 25°C air. How much entropy is generated in the chip?

A)4.19 j/k
B)5.19 j/k
C)6.19 j/k
D)7.19 j/k

Answer 1

6.19 j/k

Question 2

Second law efficiency can also be given as

A)1 / ( first law efficiency * carnot efficiency)
B)carnot efficiency * first law efficiency
C)carnot efficiency / first law efficiency
D)first law efficiency / carnot efficiency

Answer 2

first law efficiency / carnot efficiency

Question 3

Second law efficiency is defined as

A)actual exergy intake / minimum exergy intake
B)minimum exergy intake / actual exergy intake
C)actual exergy intake / maximum exergy intake
D)maximum exergy intake / minimum exergy intake

Answer 3

minimum exergy intake / actual exergy intake

Question 4

For a power plant, second law efficiency can be given by desired output(W) / available energy(Wmax).

Question 5

In case of a heat pump, second law efficiency is given as

A)(first law efficiency)*(1-ta/to)
B)(first law efficiency)*(1+to/ta)
C)(first law efficiency)*(1-to/ta)
D)none of the mentioned

Question 6

Both first law efficiency and second law efficiency indicate how effectively the input has been converted into the product.

Question 7

Which of the following curves meet at triple point?

A)fusion curve and vaporization curve
B)fusion curve and sublimation curve
C)vaporization curve and sublimation curve
D)fusion curve and vaporization curve and sublimation curve

Question 8

The slope of the fusion curve for water is

A)negative
B)positive
C)zero
D)none of the mentioned

Question 9

The equation which forms the basis of the Mollier diagram is

A)tds=-dh+vdp
B)tds=dh+vdp
C)tds=dh-vdp
D)none of the mentioned

Question 10

Which of the following statements is true?

A)the slope of an isobar on h-s coordinates is equal to the absolute saturation temperature at that pressure
B)is the temperature remains constant, the slope will also remain constant
C)if the temperature increases, the slope of the isobar will also increase
D)all of the mentioned

Question 11

Which of the following represents the latent heat of vaporization at a particular pressure.

A)hf-hg
B)hg-hf
C)hf+hg
D)none of the mentioned

Question 12

At critical pressure, value of Hg-Hf is

A)two
B)one
C)zero
D)infinity

Question 13

In the Mollier diagram, the constant pressure lines diverge from one another.

Question 14

Which of the following is a property of a pure substance?

A)it has constant chemical composition throughout its mass
B)it is a one-component system
C)it may exist in one or more phases
D)all of the mentioned

Question 15

For water, as temperature increases, volume always increases?

Question 16

Which of the following exists in a p-V diagram for water?

A)saturated solid line
B)saturated liquid lines
C)saturated vapour line
D)all of the mentioned

Question 17

The isotherm passing through the critical point is called the critical isotherm.

Question 18

The properties of water are arranged in the steam tables as functions of

A)pressure
B)temperature
C)pressure and temperature
D)none of the mentioned

Question 19

The internal energy of saturated water at the triple point is

A)1
B)0
C)-1
D)infinity

Question 20

The entropy of saturated water is chosen to be zero at triple point.

Question 21

When a liquid and its vapour are in equilibrium at a certain pressure and temperature, then which of the following is required to identify the saturation state.

A)pressure
B)temperature
C)both pressure and temperature
D)pressure or temperature

Question 22

Saturated liquid or the saturated vapour has how many independent variables?

A)one
B)two
C)three
D)none of the mentioned

Question 23

If data are required for intermediate temperatures or pressures, linear interpolation is normally accurate.

Question 24

The superheat or degree of superheat is given by

A)difference between the temperature of saturated liquid and saturation temperature
B)difference between the temperature of superheated vapour and saturation temperature
C)sum of the temperature of superheated vapour and saturation temperature
D)none of the mentioned