Heat And Thermodynamics
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
A temperature may be measured by using a constant volume gas thermometer and measuring the pressure of the gas both at the triple point of water and at the unknowntemperature.
Which one of the following procedures is necessary if two gas thermometers, using different real gases, are to agree
Take readings at very low pressures in both thermometers.
Use the same mass of gas in both thermometers.
Use gases of the same density in both thermometers
Use gases of the same specific heat capacity in both thermometers.
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
Measurements of the radiation from an astronomical source showed a decrease in the wavelength at which the greatest energy was beingreceived.
This could mean that the source had
expanded but maintained a constant temperature
increased in temperature
decreased in temperature
contracted but maintained a constant temperature
A system absorbs 1000 cal of heat and does 1675 J of externalwork.
If J = 4.18 J/cal, then the change in internal energy of the system is
+ 650 J
+ 1000 J
+ 1675 J
+ 2505 J
A bimetal made of copper and iron strips welded together is straight at roomtemperature.
It is held vertically in the hand so that iron strip is towards the left hand and copper strip is towards the right handside.
This bimetal is then heated byflame.
The bimetal strip will
bend towards left
bend towards right
A gas at pressure P is adiabatically compressed so that its density becomes twice that of initialvalue.
Given that the ratio of specific heats at constant pressure and constant volume is 7/5. What will be the final pressure of the gas
7P / 5
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
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
Two thermometers X and Y are placed inside an enclosure whose walls are maintained at a steady temperature T. When equilibrium is established, X and Y will give the same reading T
only if both are perfect absorbers
only if they have equal thermal capacities
only if they absorb radiation at equal rates
under all circumstances
A Carnot engine working between 300 K and 600 K has a work output of 800 J percycle.
The amount of heat energy supplied from the source to the engine in each cycle is
An ideal gas with pressure P is compressed isothermally till the mean separation between molecules of the gas is reduced to half of the originalvalue.
The final pressure will be
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)
L / g
3L / g
2L / g
4L / g
In a thermodynamic process, the pressure of a fixed mass of gas is changed in such a manner that the gas molecules give out 30 J of heat and 10 J of work is done on thegas.
If the initial internal energy of the gas was 40 J, then the final internal energy will be
- 20 J
In the case of saturated vapour
pressure varies linearly with temperature at constant volume
pressure becomes less than one atmosphere at boiling point
pressure varies non-linearly with temperature at constant volume
pressure depends upon volume at constant temperature
If gas is compressed adiabatically
the internal energy of gas increases
the work done is positive
the internal energy of gas does not change
the internal energy of gas decreases
The thermal resistance of two blocks connected in series will be, if their separate thermal resistances are 2 and 3 is
Pyrometer is an instrument used to measure
During an isothermal expansion of an ideal gas
the work done by the gas is equal to the quantity of heat absorbed by it
both B and C are correct
its internal energy decreases
its internal energy does not change
Increase of pressure
always decreases the melting point of solid
increases the melting point of solid which expand on melting
always increases the melting point of solid
always increases the boiling point of a liquid
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