Thermodynamics Set 5 MCQs

Q1 | 287 J/kg/?k is the value of

Gas constant in MKS units

Gas constant in S.I. units

Universal gas constant in MKS units

Universal gas constant in S.I. units

None of the above

Q2 | The velocity potential exists

Only for unidirectional flow

Only for rotational flow

For all types of continuous flow

Only for laminar flow

Only for irrotational flow

Q3 | The number of degrees of freedom in case of diatomic gases is

2

3

5

6

4

Q4 | Which of the following statement is correct?

Both heat and work are path functions

Pulsejet

Systems never possess heat but work can be

While work is a boundary phenomenon heat is not

Both heat and work are inexact differentials

Q5 | Identify the correct statement

All substances emit radiation the quality and quantity depends on the absolute temperature and properties of the material composing the radiating body

Only some substances emit radiation

Quality and quantity of radiation depends on the properties of the material only

A substance will emit radiation at a particular wavelength only

Bodies black in colour are known as black bodies in radiation

Q6 | Which of the following changes during throttling process?

Pressure

Temperature

Internal energy

Pressure x Volume

All of the above

Q7 | The molecular weights of all the perfect gases occupy the same volume under same conditions of pressure and temperature".

Boyle's law

Regnault's law

Avogadro's hypothesis

Balton's law

Gay Lussac's law

Q8 | In which case the heat transferred from the air when compressed from 1.05 ata 15?C to 6.3 ata would be minimum?

Adiabatic

Polytropic pv1.3 = C

Polytropic pv1.31 = C

Polytropic pv1.35 = C

Isothermal

Q9 | The specific heat of water

Decreases with rise of temperature

First increases, reaches a maximum value and then decreases.

Increases with rise of temperature

First decreases, reaches a minimum value and then increases

Does not change with temperature

Q10 | If during a process the entropy of a isolated system increases, the process is

Ideal

Reversible

Irreversible

Polytropic

None of the above

Q11 | The number of processes in a Rankine cycle is

Four

Five

Three

Six

Two

Q12 | Ericsson cycle processes are

Two adiabatic, constant volume and constant pressure

Two isothermals and two constant pressures

Two isothermals and two isentropics

Two isothermals and two constant volumes

Two isothermals and two isentropics

Q13 | In a Joule cycle, the heat is rejected at

Constant pressure

Constant enthalpy

Constant temperature

Constant volume

Constant entropy

Q14 | Isentropic flow is

Irreversible adiabatic flow

Ideal fluid flow

Change in entropy is zero

Frictionless reversible flow

Perfect gas flow

Q15 | The triple point for carbondioxide is at about -56.7 C and about 5 atm, pressure. It means that

Mass transfer at triple point is maximum

When CO2 is exposed to a below 5 atmosphere pressure only solid and liquid phase exist together

Above 56.7 C CO2 exists only as a liquid

Below 57.7 C CO2 exists only in liquid form

When solid CO2 is exposed to 1 atm pressure it begins to change directly to gas

Q16 | In a reversible cycle, the entropy of the system

Depends on the properties of working substance

Decreases

Does not change

Increases

First increases and then decreases

Q17 | The first law of thermodynamics, for steady flow

Accounts for all energy entering and leaving a control volume

Is primarily concerned with heat transfer

Is restricted in its application to perfect gases

Is an energy balance for the specified mass of fluid

Is an expression of the conservation of linear momentum

Q18 | The unit of universal gas constant is

dynes/?K

erg/?K

W/m?K

kcal/?K

W/?K

Q19 | Which of the following is not a characteristic of liquid air?

It will cause rubber to become brittle

Pulsejet

It will freeze mercury and ammonia

It has no surface tension

It will separate out lead from solder

Q20 | Which of the following relation does not hold good for a throttling process?

dQ = 0

dS = 0

Pulsejet

dH = 0

dW = 0

Q21 | According to Amagat's law

the sum of the volume friction is unity

there would be no volume change if the components are mixed while holding the temperature and pressure constant

all diatomic gases occupy double the volume of monoatomic gases for identical masses

None of the above

Pulsejet

Q22 | In the polytropic process pvn = Constant if n = 1 the process is termed as

Adiabatic

Constant pressure

Constant temperature

Constant volume

Isothermal

Q23 | Otto cycle consists of the set of processes as

Two isentropics and two constant volumes

Two isothermal and two constant volume

Two isentropics and two constant pressure

Two adiabatic and two isothermal

Two isothermal and two constant pressure

Q24 | If the two specific heats of a gas are 0.237 and 0.169 respectively, the volume of 3 kg of air at 27?C under a pressure of 3 ata would be

2.5 cu-m

1 cu-m

0.204 cu-m

1.74 cu-m

1.5 cu-m

Q25 | Five people must be lifted in an elevator to a distance of 100 m. The work is found to be 341.2 kJ and the gravitational acceleration is 9.75 m/s2. The average mass per person is

Pulsejet

72 kg

70 kg

67.5 kg

65 kg