1.
The latent heat of vaporization at critical point is
Correct Answer
C. 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.
2.
With increase in pressure
Correct Answer
B. 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.
3.
Dryness fraction of steam is defined as
Correct Answer
C. 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.
4.
The specific volume of water when heated at 0°C
Correct Answer
B. 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.
5.
Only throttling calorimeter is used for measuring
Correct Answer
D. 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.
6.
The properties of water are arranged in the steam tables as functions of
Correct Answer
C. Pressure and temperature
Explanation
The properties of water, such as density, specific heat, and enthalpy, vary with both pressure and temperature. Therefore, in steam tables, these properties are arranged as functions of both pressure and temperature. This is because the behavior of water changes significantly with changes in both pressure and temperature, and it is important to have accurate data for engineering and thermodynamic calculations.
7.
When does a vapour become super heated?
Correct Answer
B. When the temperature of vapour is more than the saturation temperature at given pressure
8.
The superheat or degree of superheat is given by
Correct Answer
B. 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.
9.
Which of the following statements is true? In case of Dryness fraction.
Correct Answer
D. 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.
10.
The internal energy of saturated water at the triple point is
Correct Answer
B. 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.