Questions and Answers on Thermodynamics

A single fixed point temperature scale is based on
(a) ice point
(b) steam point
(c) triple point of water
(d) critical point of water
(Answerwer:c)
Which of the following correctly defines 1K, as per the internationally accepted definition of the temperature scale?
(a) (1/100)th of the difference between normal boiling point and normal freezing point
(b) (1/273.15)th of the normal freezing point of water
(c) 100 times the difference between the triple point of water and normal freezing point of water
(d) (1/273.16)th of triple point of water
(Answerwer:d)
Which thermometer is independent of the substance or material used in its construction?
(a) mercury thermometer
(b) alcohol thermometer
(c) ideal gas thermometer
(d) resistance thermometer
(Answer:c)
A system is capable of exchanging energy with its surroundings in the form of non reversible work modes. The number of independent variables that completely specify the state of the system is
(a) n-2
(b) n-1
(c) n
(d) n+1
(Answer:d)
If δQ is the heat trAnswerferred to the system and δW is the work done by the system, then which of the following is an exact differential
(a) δQ
(b) δW
(c) δQ + δW
(d) δQ – δW
(Answer:d)
Air enters an adiabatic nozzle at 400 kPa and 900 K with negligible velocity. If the flow is ideal and exit pressure is 100 kPa, the exit temperature in K and exit velocity in m/s are respectively
(a) 605.7, 768.7
(b) 225, 1164.8
(c) 516.9, 877.5
(d) 129.2, 880.1
(Answer:a)
170 kJ of heat is supplied to a system at constant volume. Then the system rejects 180kJ of heat at constant pressure and 40kJ of work is done on it. The system is finally brought to its original state by an adiabatic process. If the initial value of internal energy is 100kJ, then which one of the following statements is correct?
(a) the highest value of internal energy occurs at the end of the constant volume process
(b) the highest value of internal energy occurs at the end of the constant pressure process
(c) the highest value of internal energy occurs after adiabatic expAnswerion
(d) internal energy is equal at all the points
(Answer:a)
In a given process of an ideal gas, δW = 0 and δQ<0, Then for the gas
(a) the temperature will decrease
(b) the volume will increase
(c) the pressure will remain constant
(d) the temperature will increase
(Answer:a)
According to the Clausius statement of second law of thermodynamics, the COP of a refrigerator is never
(a) ∞
(b) 1
(c) <1
(d) ˃1
(Answer:a)
A process ‘A’ is irreversible and adiabatic. Process ‘B’ is reversible and adiabatic. The entropy change in process ‘A’ and process ‘B’, respectively are
(a) zero and positive
(b) zero and negative
(c) negative and zero
(d) positive and zero
(Answer:d)
Which of the following statements is FALSE?
(a) a mixture of an ideal gas also behaves as an ideal gas
(b) the enthalpy of an ideal gas is a function of temperature only
(c) the entropy of an ideal gas is a function of temperature only
(d) the temperature of an ideal gas always decreases during isentropic expAnswerion
(Answer:c)