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Heat And Thermodynamics
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Let's practice 30 mcqs on
Heat And Thermodynamics
mcqs by everyone
If gas is compressed adiabatically
the internal energy of gas does not change
the work done is positive
the internal energy of gas increases
the internal energy of gas decreases
A block of mass 100 g slides on a rough horizontalsurface.
If the speed of the block decreases from 10 m/s to 5 m/s the thermal energy developed in the process is
0.375 J
0.75 J
3.75 J
37.5 J
The molecular weight of gas is 44. The volume occupied by 2.2 g of this gas at 0 degreeCentigrade and 2 atm pressure, will be
0.56 L
2.4 L
1.2 L
5.6 L
One mole of an ideal gas requires 207 J heat to raise the temperature by 10 K when heated at constantpressure.
If the same gas is heated at constant volume to raise the temperature by the same 10 K, then the heat required is
24 J
124 J
215.3 J
198.7 J
A gas behaves more closely as an ideal gas at
high pressure and high temperature
high pressure and low temperature
low pressure and low temperature
low pressure and high temperature
For a perfect gas if
P and V are given T is uniquely determined
T is given V is uniquely determined
T is given P is uniquely determined
T is given P and V both are uniquely determined
Only a very small fraction of the energy supplied to a domestic light bulb is emitted aslight.
This is because
the filament is not a black body
most of the energy is given out at shorter wavelengths
most of the energy is given out at longer wavelengths
the filament surface area is too small to emit light efficiently
The most efficient heat engine is one which is
None of the above
irreversible
Reversible
driven by high speed diesel
The pressure of a gas kept in an isothermal container is 200kPa.
If half the gas is removed from it, the pressure will be
400 kPa
100 kPa
200 kPa
800 kPa
The thermal resistance of two blocks connected in series will be, if their separate thermal resistances are 2 and 3 is
1.5
1
6
5
For an isolated system
temperature is constant
All of These
pressure is constant
volume is constant
The temperature of a substance increases by 27 degreeCentigrade.
On the Kelvin scale this increase is equal to
300 K
27 K
7K
2.46 K
Pyrometer is an instrument used to measure
latent heat
high temperatures
low temperatures
specific heat
The molar heat capacity of an ideal gas at constant pressure is greater than that at constant volume because
work has to be done against external pressure as the gas expands
work has to be done against intermolecular forces as the gas expands
the molecules gain rotational kinetic energy as the gas expands
If same amount of heat is supplied to two identical spheres (one is hollow and other is solid), then
the expansion in hollow is greater than the solid
the temperature of both must be same to each other
the expansion in hollow is lesser than the solid
the expansion in hollow is same as that in solid
When without change in temperature a gas is forced in a smaller volume, its pressure increases because its molecules
strike the unit area of container wall with greater force
have more energy
strike the unit area of the container wall at higher speed
strike the unit area of the container wall more often
Which of the following quantities is zero on an average for the molecules of an ideal gas in equilibrium
Speed
Kinetic Energy
density
Momentum
What work will be done, when 3 moles of an ideal gas are compressed to half the initial volume at a constant temperature of 300 K
5000 J
-5188 J
-5000 J
5188 J
At what temperature is the effective speed of gaseous hydrogen molecules equal to that of oxygen molecules at 47 degreeCentigrade
50 K
40 K
100 K
20 K
Two thermometers are constructed in such a way that one has a spherical bulb and other has elongated cylindricalbulb.
The bulbs are made of same material andthickness.
Then
spherical bulb will respond more quickly to temperature changes
cylindrical bulb will respond more quickly to temperature changes
none of both bulbs respond to temperature changes
both bulbs will respond same to temperature changes
The internal energy U is a unique function of any state because change in U
does not depend upon path
corresponds to an isothermal process
depend upon path
corresponds to an adiabatic process
The wax melts up to lengths 105 cm and 60 cm for two indentical rods of different metals in Ingen Hauszexperiment.
The ratio of thermal conductivities of the two metals is
7 : 4
49 : 16
16 : 49
4 : 7
If the amount of heat given to a system be 35 J and the amount of work done by the system be - 15 J, then the change in the internal energy of the system is
20 j
30 J
50 J
- 50 J
Two cylinders A and B fitted with pistons contain equal amounts of an ideal diatomic gas at 300 K. The piston of A is free tomove.
The piston of B is heldfixed.
The same amount of heat is given to the gas in eachcylinder.
If the rise in temperature of the gas in A is 30 K, then the rise in temperature of the gas in B is
42 K
30 K
50 K
18 K
During the adiabatic expansion of 2 mol of a gas, the internal energy was found to have decreased by 100 J. The work done by the gas in this process is
100 J
- 100 J
Zero
200 J
A monoatomic ideal gas expands at constant pressure, with heat Qsupplied.
The fraction of Q which goes as work done by the gas is
2 / 5
2 / 3
1
3 / 5
Internal energy of ideal gas depend on
only temperature
only volume
only pressure
NONE OF THESE
A vessel containing 5 litre of a gas at 0.8 m pressure is connected to an evacuated vessel of volume 3litre.
The resultant pressure inside will be
(assuming whole system to be isolated)
� m
2.0 m
4/3 m
0.5 m
Latent heat of vaporization is the energy required to
force back the atmosphere to make space for the vapour
separate the molecules and to force back the atmosphere
separate the molecules of the liquid
increase the average molecules speed in the liquid phase to that in the gas phase
From what height should a piece of ice fall so that it melts completely ? (Given : one-quarter of the heat produced is absorbed by ice and latent heat is L)
4L / g
L / g
2L / g
3L / g
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