13 April 2010

Heat and Thermodynamics

UNIT - I
1. What is heat?
a. Heat is a substance called calorie which flows from heavy body
to a light body.
b. Heat is energy that flows from a high temperature body to a low
temperature body.
c. Heat is a motion that passes from a moving body to a stationary
body.
d. Heat is a field passing from high potential body to a low
potential body.
2. If the temperature of patient is 40°C, his temperature on the
Fahrenheit scale will be
a. 104°F b. 72°F c. 96°F d. 100°F
3. The temperature of a block of iron is 140°F. Its temperature the
Celsius scale is
a. 108° b. 32° c. 60° d. 140°
4. The temperature at which centigrade and Fahrenheit scales give the
same reading is
a. 40°C b. 40°R c. -40°C d. 40°F
5. In a resistance thermometer, the resistances at 0°C and 100°C are
6.74 and 7.74 ohms respectively. The temperature corresponding to 6.53 ohms resistance is
a. +53°c b. +21°C c. -53°C d. -21°C
6. No other thermometer is suitable as a platinum resistance
thermometer to measure temperature in the entire range of
a. -50°C to +350°C b. -200°C to +600°C
c. o°C to 100°C d. 100°C to 1500°C
7. For measurement of temperature of the order of 400°C, we will prefer
a. Mercury thermometer b. Alcohol thermometer
c. Radiation thermometer d. Thermocouple
8. The bulb of the Callendar’s compensated constant pressure air
thermometer is 800cm3. When the bulb is immersed in a bath,
200cm3 of mercury has to be drawn out of the reservoir. The
temperature of the bath on the Celsius scale is
a. 33.33°C b. 91°C c. 364°C d. none of the above
9. A constant volume gas thermometer works on
a. Archimedes principle b. Boyle’s law c. Pascal’s law
d. Charles’s law
10. A constant volume gas thermometer shows pressure reading of 50cm
and 90 cm of mercury at 0°C and 100°C respectively. When the pressure reading is 60cm of mercury, the temperature is
a. 25°C b. 40°C c. 15°C d.12.5°C
11. The ratio of any two temperatures on this scale is equal to the ration
of the heats absorbed and rejected by a Carnot reversible engine working between these two temperatures. Such a temperature scale is called_____________
a. Kelvin scale b. Celcius Scale c. Reaumer Scale d. none
12. The branch of heat dealing with measurement of temperature is
called ____________
a. Thermometry b. Callorimetry C. Plasticity d. none
13. ____________ is an instrument used to measure the temperature of
a body.
a. Thermometer b. Pyrometer c. Callorimeter d. none
14. The relation between Celsius and Reaumur scale is
a. (C/100)=(R/80) b. (R/100)=(C/80) c. (C/100)=(R/180) d. none
15. Fahrenheit Scale is used in
a. Medical b. Scandinavian Countries c. Internationally
d. none of the above
Answers:
1) b 2) a 3) c 4) c 5) d 6) b 7) d 8) b 9) d 10) a 11) a
12) a 13) a 14) a 15) a


UNIT – II
1. The number of degrees of freedom of Nitrogen molecule (N2) is
a) 2 b) 3 c) 5 d) 7
2. On the basis of kinetic theory of gases, the mean K.E of 1 mol per
degree of freedom is
a) (1/2) RT b) (3/2) RT c) (1/2) KT d) (3/2) KT
3. Oxygen and Hydrogen gases are at the same temperature T. The
Kinetic energy of an oxygen molecule will be equal to
a) 16 times the KE of a hydrogen molecule
b) 4 times the KE of a hydrogen molecule
c) The KE of a hydrogen molecule
d) One fourth the KE of a hydrogen molecule
4. The value of the ratio of specific heat capacities for rigid triatomic
molecule is
a) 1.75 b) 1.66 c) 1.4 d) 1.33
5. The average distance traveled by a molecule between two successive
collisions is called
a) Wavelength b) mean free path c) free path
d) Molecular diameter
6. The mean free path of a gas varies with absolute temperature as
a) T b) T-1 c) T2 d) T4
7. The mean free path of a gas molecule is inversely proportional to
a) square of the diameter of the molecule
b) square root of the diameter of the molecule
c) molecular diameter
d) fourth power of molecular diameter
8. The mean free path of a gas varies with pressure as
a) P b) P-1 c) P-2 d) P2
9. The viscosity of a gas is directly proportional to
a) temperature b) square root of temperature
c) characteristic gas constant d) density of the gas
10. Diffusion of gases is mainly due to
a) Newton’s law of cooling b) Pressure difference
c) Joule-Kelvin effect d) A concentration gradient of the
molecules
11. The coefficient of diffusion is directly proportional to
a) T3/2 b) T1/2 c) T2/3 d) none of these
12. Example for non-linear molecule is
a) H2O b) CO2 c) CS2 d) none of these
13. Example for microscopic properties of the gas molecule is
a) speeds b) pressure c) temperature d) none of these
14. The KE of the gas is proportional to the absolute
a) temperature b) pressure c) volume d) none of these
15. The total number of independent coordinates required to specify
completely its position and configuration is called
a) degrees of freedom b) equipartition of energy
c) Maxwell distribution law d) none of these
Answers:
1) c 2) a 3) c 4) d 5) b 6) a 7) a 8) b 9) b 10) d 11) a
12) a 13) a 14) a 15) a
UNIT – III
1. In the general gas equation PV=RT, Vander Waals introduced a
correction factor a/V2 in pressure. The term a/V2 represents
a) Effective area of molecules b) Mean velocity of gas molecules
c) Volume occupied by molecules d) Attraction force between molecules
2. Critical temperature can be defined as
a) Temperature at which all motion of gas ceases
b) Temperature at which a gas is converted into liquid
c) Temperature at which volume of gas becomes zero
d) Temperature above which a gas can not be liquefied no matter how
high pressure may be.
3. The value of (RT/PV) for a gas obeying Vander Waal’s equation is
a) 8/3 b) 3/8 c) 1 d) 0.5
4. The relation between temperature of inversion (Ti) and Boyle
temperature (TB) is
a) Ti=2TB b) Ti=TB c) 2Ti=TB d) TiTB=1
5. The relation between temperature of inversion (Ti) and critical
temperature (Tc) is
a) Ti=6.75Tc b) Ti=2Tc c) Ti=Tc d) 1/Tc
6. If a gas under constant pressure is allowed to pass through an
insulated porous plug to a region of constant low pressure, the
temperature of escaping gas changes. This effect is called
a) Feltier effect b) Kelvin effect c) Joule Thomson effect
d) none of the above.
7. Critical Volume (Vc) is the reciprocal of the
a) critical density b) temperature c) gas constant d) none
8. The Critical Pressure (Pc) is (a/27b2)
9. The Critical Volume (Vc) for argon gas is
a) 3b b) 1.4b c) 2.8b d) 5b
10. If two gases have the same reduced pressure and volume, they will
also have the same reduced
a) temperature b) momentum c) viscosity d) potential
11. Two gases are said to be in corresponding sates if the ratios of their
actual pressure, volume and temperature and critical pressure,
critical volume and critical temperature have the
a) same value b) different value c) reciprocal of its value
d) none of the above.
12. The fall in temperature becomes zero at a particular temperature
called the
a) temperature of inversion b) critical temperature
c) critical pressure d) critical volume
13. If (2a/RT)>b, then dT is positive. Hence there will be a
a) cooling or heating effect b) heating effect c) cooling effect
d) none of these
14. The inversion temperature (Ti) is
a) (2a/Rb) b) (4a/Rb) c) (8a/Rb) d) (a/Rb)
15. The temperature of inversion for hydrogen is
a) -800°C b) -60°C c) -180°C d) -80°C
Answers:
1) d 2) d 3) a 4) a 5) a 6) c 7) a 9) b 10)a 11) a
12) a 13) c 14) a 15) d
UNIT – IV
1. If a hot body is placed in vacuum, it cannot lose heat by
a) conduction b) radiation c) emission d) none
2. The average wavelength of thermal radiation is greater than that of
a) ultra violet b) visible light c) infrared d) x-ray
3. The unit for total emissive power is
a) Jm-3s-1 b) Jm-1s-1 c) Jm-2s-1 d) none
4. ________________ is the radiant energy of all wave lengths emitted per
unit time from unit surface area of a radiating body.
a) spectral emissive power b) Stefan law
c) Boltzmann law d) Total emissive power
5. A perfectly ____________ is one which absorbs all the heat radiations,
of whatever wavelength, incident on it.
a) black body b) red body c) yellow body d) green body
6. The nature of radiation becomes _____________ of the shape, size and
material of the body.
a) dependent b) independent c) reciprocal d) none
7. The nature of radiation depends only upon the ___________ of the body.
a) size b) shape c) temperature d) all of these
8. The total amount of heat radiated by a perfectly black-body per second
per unit area is ____________ proportional to the fourth power of its absolute temperature.
a) inversely b) directly c) naturally d) none
9. The value of relative emittance (e) varies between
a) 0 and 1 b) -1 and +1 c) -1 and 0 d) 0 and 2
10. At what temperature a black body will radiate thermal energy at the

rate of 1 watt per square cm?
a) 598 K b) 487 K c) 648 K d) 785 K
11. _____________ is defined as the amount of solar energy received per
second by unit area of a perfectly black surface, held perpendicular to the sun’s rays and placed at a mean distance of the earth from the sun, in the absence of the atmosphere.
a) Solar constant b) Stefan constant
c) Rayleigh constant d) none of these
12. The solar constant is determined by using
a) resistance thermometer b) water flow pyroheliometer
c) Jolly’s constant volume thermometer d) none of these
13. The value of So is

a) 1400 Jm-2s-1 b) 1800 Jm-2s-1 c) 2000 Jm-2s-1 d) none
14. For a perfectly black body the relative emittance is
a) zero b) one c) two d) none of these
15. The solar spectrum was first observed by
a) Bohr b) Einstein c) Newton d) Homi J. BhaBha
16. Fraunhofer lines can be explained by applying the
a) principle of reversal b) newton’s law c) cooling method d) none
17. The Photosphere is surrounded by a gaseous envelope called the _____________ whose temperature is about 6000K.
a) telluric lines b) chromosphere c) fraunhofer lines d) none
Answers:
1) a 2) b 3) c 4) d 5) a 6) b 7) c 8) b 9) a 10) c
11) a 12) b 13) a 14) b 15) c 16) a 17) b


UNIT – V
1. The conduction of heat from hot body to a cold body is an example of
a) reversible process b) irreversible process
c) quasistatic process d) none of the above
2. The total gain in entropy of the working substance in Carnot’s cycle is
a) zero b) negative c) positive d) none of the above
3. A piece of ice is added to water in a cup. The entropy
a) is increased b) is decreased
c) undergoes no change d) does not enter into picture
4. The ratio of adiabatic and isothermal elasticities for any substance is
equal to
a) Cp b) zero c) Cp-Cv d) Cp/Cv
5. The process will not be reversible if there is any loss of heat due to
a) friction b) acceleration c) velocity d) none
6. It is impossible for an engine unaided by external agency to transfer
heat from one body to another at a higher temperature. This statement is called
a) Maxwell statement b) Heisenberg statement
c) Clausius statement d) Kelvin- Plank statement
7. The second law of thermodynamics tells us that many processes are
a) reversible b) cyclic c) isolated d) irreversible
8. The unit for entropy is
a) JK-3 b) JK-1 c) JK2 d) none of these
9. The total change of entropy is _________ during a Carnot cycle of
operations.
a) two b) four c) infinity d) zero
10. The entropy of a system increases in all irreversible processes. This is
known as the law of
a) increase of entropy b) decrease of entropy c) zeroth law d) none of these

11. The second law of thermodynamics is
a) dQ = T dS b) dS = T dQ c) T dQ = dS d) none
12. Calculate the change in entropy when 0.05 kg of steam at 100°C is

converted to water at the same temperature.
a) 302.9JK-1 b) 562.9JK-1 c) 403.9JK-1 d) none
13. The energy of the molecules at absolute zero temperature is called
a) internal energy b) free energy c) zero point energy d) none
14. The formula for Enthalpy (H) is
a) U+PV b) TdS+VdP C) TdS- VdP d) VdS+TdP
15. 10-2 kg of water is heated from 0°C to 100°C. Compute the change in
entropy.
a) 13.08JK-1 b) 18.23JK-1 c) 32JK-1 d) 65.36JK-1
16. It is impossible to construct a device which, operating in a cycle, has
the sole effect of extracting heat from a reservoir and performing an equivalent amount of work. This statement is called
a) Maxwell statement b) Kelvin- Plank statement
c) Clausius statement d) Heisenberg statement
Answers:
1) b 2) a 3) a 4) d 5) a 6) c 7) d 8) b 9) d 10) a
11) a 12) a 13) c 14) a 15) a 16) b