Heat and Thermodynamics

Two moles of helium gas are taken over the cycle \(ABCD\), as shown in the \(P\)-\(T\) diagram.

The net work done on the gas in the cycle \(ABCDA\) is:

The speed of sound in oxygen \(\left( {{O_2}} \right)\) at a certain temperature is \(460\,\,m{s^{ - 1}}.\) The speed of sound in helium \((He)\) at the same temperature will be (assume both gases to be ideal)

An insulated container of gas has two chambers separated by an insulating partition. One of the chambers has volume \({V_1}\) and contains ideal gas at pressure \({P_1}\) and temperature \({T_1}\). The other chamber has volume \({V_2}\) an...

A Carnot engine, having an efficiency of \(\eta = 1/10\) as heat engine, is used as a refrigerator . If the work done on the system is \(10\) \(J\), the amount of energy absorbed from the reservoir at lower temperature is

One end of a thermally insulated rod is kept at a temperature \({T_1}\) and the other at \({T_2}\). The rod is composed of two sections of length \({L_1}\) and \({L_2}\) and thermal conductivities \({K_1}\) and \({K_2}\) respectively. The t...

When a system is taken from state \(i\) to state \(f\) along the path iaf, it is found that \(Q=50\) cal and \(W=20\) \(cal\). Along the path \(ibf\) \(Q=36\) \(cal.\) \(W\) along the path \(ibf\) is

If \({C_p}\) and \({C_v}\) denote the specific heats of nitrogen per unit mass at constant pressure and constant volume respectively, then

Two rigid boxes containing different ideal gases are placed on a table. Box A contains one mole of nitrogen at temperature \({T_0},\) while Box contains one mole of helium at temperature \(\left( {{7 \over 3}} \right){T_0}.\) The boxes are ...

The work of \(146\) \(kJ\) is performed in order to compress one kilo mole of gas adiabatically and in this process the temperature of the gas increases by \({7^ \circ }C.\) The gas is $$\left( {R = 8.3J\,\,mo{l^{ - 1}}\,{K^{ - 1}}} \right)...

Assuming the Sun to be a spherical body of radius \(R\) at a temperature of \(TK\), evaluate the total radiant powered incident of Earth at a distance \(r\) from the Sun
Where r0 is the radius of the Earth and \(\sigma\) is Stefan's consta...

The figure shows a system of two concentric spheres of radii \({r_1}\) and \({r_2}\) are kept at temperatures \({T_1}\) and \({T_2}\), respectively. The radial rate of flow of heat in a substance between the two concentric spheres is propor...

A system goes from \(A\) to \(B\) via two processes \(I\) and \(II\) as shown in figure. If \(\Delta {U_1}\) and \(\Delta {U_2}\) are the changes in internal energies in the processes \(I\) and \(II\) respectively, then

The temperature-entropy diagram of a reversible engine cycle is given in the figure. Its efficiency is

Which of the following is incorrect regarding the first law of thermodynamics?

A gaseous mixture consists of \(16\) \(g\) of helium and \(16\) \(g\) of oxygen. The ratio \({{Cp} \over {{C_v}}}\) of the mixture is

Two thermally insulated vessels \(1\) and \(2\) are filled with air at temperatures \(\left( {{T_1},{T_2}} \right),\) volume \(\left( {{V_1},{V_2}} \right)\) and pressure \(\left( {{P_1},{P_2}} \right)\) respectively. If the value joining t...

Time taken by a \(836\) \(W\) heater to heat one litre of water from \(10{}^ \circ C\) to \(40{}^ \circ C\) is

One mole of ideal monatomic gas \(\left( {\gamma = 5/3} \right)\) is mixed with one mole of diatomic gas \(\left( {\gamma = 7/5} \right)\). What is \(\gamma\) for the mixture? \(\gamma\) Denotes the ratio of specific heat at constant pr...

Which of the following statements is correct for any thermodynamic system ?

If the temperature of the sun were to increase from \(T\) to \(2T\) and its radius from \(R\) to \(2R\), then the ratio of the radiant energy received on earth to what it was previously will be

The temperature of the two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity \(K\) and \(2K\) and thickness \(x\) and \(4x,\) respectively, are \({T_2}\) and $${T_1}\left( {{T_2} > {...

Which of the following parameters does not characterize the thermodynamic state of mattter?

A carnot engine takes \(3 \times {10^6}\) cal. of heat from a reservoir at \({627^ \circ }C,\) and gives it to a sink at \({27^ \circ }C\). The work done by the engine is

The earth radiates in the infra-red region of the spectrum. The spectrum is correctly given by

''Heat cannot by itself flow from a body at lower temperature to a body at higher temperature'' is a statement or consequence of :

During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its absolute temperature. The ratio \({C_p}/{C_V}\) for the gas is

Heat given to a body which raises its temperature by \({1^ \circ }C\) is

Cooking gas containers are kept in a lorry moving with uniform speed. The temperature of the gas molecules inside will

Infrared radiation is detected by

Even Carnot engine cannot give \(100\%\) efficiency because we cannot

Two spheres of the same material have radii \(1\) \(m\) and \(4\) \(m\) and temperatures \(4000\) \(K\) and \(2000\) \(K\) respectively. The ratio of the energy radiated per second by the first sphere to that by the second is

At what temperature is the \(r.m.s\) velocity of a hydrogen molecule equal to that of an oxygen molecule at \({47^ \circ }C?\)

1 mole of a gas with \(\gamma = 7/5\) is mixed with \(1\) mole of a gas with \(\gamma = 5/3,\) then the value of \(\gamma\) for the resulting mixture is

Which statement is incorrect?

Which of the following is more close to a black body?

If mass-energy equivalence is taken into account, when water is cooled to form ice, the mass of water should