Let's Check Your Knowledge Of Properties Of Steam.

2.

When does a vapour become super heated?

When the temperature of vapour is less than the saturation temperature at given pressure
When the temperature of vapour is more than the saturation temperature at given pressure
When the temperature of vapour is equal to the saturation temperature at given pressure
None of the above

Correct Answer

A. When the temperature of vapour is more than the saturation temperature at given pressure

3.

The latent heat of vaporization at critical point is

Less than zero
Greater than zero
Equal to zero
None of the above.

Correct Answer

A. Equal to zero

Explanation

The latent heat of vaporization at the critical point is equal to zero because at this point, the substance exists as a single phase with no distinction between the liquid and gas phases. The critical point represents the highest temperature and pressure at which a substance can exist as a liquid and beyond this point, it cannot be condensed into a liquid regardless of the pressure applied. Therefore, there is no energy required or released during the transition from liquid to gas at the critical point, resulting in a latent heat of vaporization equal to zero.

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4.

The superheat or degree of superheat is given by

Difference between the temperature of saturated liquid and saturation temperature
Difference between the temperature of superheated vapour and saturation temperature
Sum of the temperature of superheated vapour and saturation temperature
None of the above

Correct Answer

A. Difference between the temperature of superheated vapour and saturation temperature

Explanation

The correct answer is "difference between the temperature of superheated vapor and saturation temperature." Superheat refers to the temperature increase of a vapor above its saturation temperature. It is the difference between the actual temperature of the superheated vapor and the saturation temperature at that pressure. This indicates how much the vapor has been heated beyond its boiling point at a given pressure.

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5.

Which of the following statements is true? In case of Dryness fraction.

The value of x varies between 0 and 1
For saturated water, x=0
For saturated vapour, x=1
All of the mentioned

Correct Answer

A. All of the mentioned

Explanation

The statement "all of the mentioned" is the correct answer because in the case of dryness fraction, the value of x does indeed vary between 0 and 1. For saturated water, the dryness fraction is 0, indicating that the water is completely liquid. For saturated vapor, the dryness fraction is 1, indicating that the vapor is completely dry and devoid of any liquid water. Therefore, all the statements mentioned in the options are true.

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6.

Dryness fraction of steam is defined as

Mass of water vapour in suspension/(mass of water vapour in suspension + mass of dry steam)
mass of dry steam/mass of water vapour in suspension
mass of dry steam/(mass of dry steam + mass of water vapour in suspension)
mass of water vapour in suspension/mass of dry steam.

Correct Answer

A. mass of dry steam/(mass of dry steam + mass of water vapour in suspension)

Explanation

The dryness fraction of steam is defined as the ratio of the mass of dry steam to the sum of the mass of dry steam and the mass of water vapor in suspension. This ratio represents the amount of dry steam present in a steam-water mixture. A higher dryness fraction indicates that the steam contains less water vapor and is therefore drier. Conversely, a lower dryness fraction indicates that the steam contains more water vapor and is therefore wetter.

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7.

The internal energy of saturated water at the triple point is

1
0
-1
Infinity

Correct Answer

A. 0

Explanation

At the triple point, water exists in a state where it can coexist in all three phases: solid, liquid, and vapor. The internal energy of a substance is the sum of its kinetic and potential energies. At the triple point, the internal energy of saturated water is at equilibrium, meaning there is no net change in energy. Therefore, the internal energy is considered to be zero.

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8.

The specific volume of water when heated at 0°C

First increases and then decreases
First decreases and then increases
Increases steadily
decreases steadily.

Correct Answer

A. First decreases and then increases

Explanation

When water is heated at 0°C, the specific volume initially decreases and then increases. This is because at 0°C, water is in its solid state (ice) and has a higher density. As heat is applied, the ice melts and transitions into liquid water. During this phase change, the specific volume decreases. However, as the temperature continues to rise, the liquid water starts to expand and its specific volume increases. Therefore, the specific volume of water first decreases and then increases when heated at 0°C.

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9.

Only throttling calorimeter is used for measuring

Very low dryness fraction upto 0.7
dryness fraction of only low pressure steam
Dryness fraction of only high pressure steam.
Very high dryness fraction upto 0.98

Correct Answer

A. Very high dryness fraction upto 0.98

Explanation

The correct answer is "very high dryness fraction upto 0.98". Throttling calorimeter is a device used to measure the dryness fraction of steam. It works by allowing the steam to expand rapidly through a small orifice, causing a drop in pressure. This drop in pressure is then used to determine the dryness fraction of the steam. Throttling calorimeters are specifically designed to measure high dryness fractions, typically up to 0.98. Therefore, the correct answer is that the only dryness fraction that can be measured using a throttling calorimeter is a very high dryness fraction up to 0.98.

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10.

With increase in pressure

Enthalpy of dry saturated steam increases
Enthalpy of dry saturated steam decreases
Enthalpy of dry saturated steam remains same
Enthalpy of dry saturated steam first increases and then decreases.

Correct Answer

A. Enthalpy of dry saturated steam decreases

Explanation

As pressure increases, the enthalpy of dry saturated steam decreases. This is because an increase in pressure leads to a decrease in the specific volume of the steam. As the specific volume decreases, the steam becomes more compressed and its enthalpy decreases.

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Let's Check Your Knowledge Of Properties Of Steam.

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

Quiz Preview

When does a vapour become super heated?

The latent heat of vaporization at critical point is

The superheat or degree of superheat is given by

Which of the following statements is true? In case of Dryness fraction.

Dryness fraction of steam is defined as

The internal energy of saturated water at the triple point is

The specific volume of water when heated at 0°C

Only throttling calorimeter is used for measuring

With increase in pressure