Second Law of Thermodynamics

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LEVELJEE Advanced

The specific heat capacity of a metal at low temperature ( $T$ ) is given as $C_{p} (kJ K^{- 1} kg^{- 1}) = 32 (\frac{T}{400})^{3}$ . A 100 g vessel of this metal is to be cooled from 20 K to 4 K by a special refrigerator operating at room temperature (27°C). The amount of work required to cool the vessel is

equal to 0.002 kJ

greater than 0.148 kJ

between 0.148 kJ and 0.028 kJ

less than 0.028 kJ

A solid body of constant heat capacity $1 J/^{\circ} C$ is being heated by keeping it in contact with reservoirs in two ways (i) Sequentially keeping in contact with 2 reservoirs such that each reservoir supplies same amount of heat. (ii) Sequentially keeping in contact with 8 reservoirs such that each reservoir supplies same amount of heat. In both the cases, body is brought from initial temperature $10 0^{\circ} C$ to final temperature $20 0^{\circ} C$ . Entropy change of the body in the two cases respectively, is

ln 2, 4 ln 2

ln 2, ln 2

ln 2, 2 ln 2

2 ln 2, 8 ln 2

"Heat cannot be itself flow from a body at lower temperature to a body at higher temperature" is a statement or consequence of

second law of thermodynamics

conservation of momentum

conservation of mass

first law of thermodynamics

An ideal gas in a cylinder is separated by a piston in such a way that the entropy of one part is $S_{1}$ and that of the other part is $S_{2}$ . Given that $S_{1} > S_{2}$ . If the piston is removed, then the total entropy of the system will be

S_{1} \times S_{2}

S_{1} - S_{2}

\frac{S _{1}}{S _{2}}

S_{1} + S_{2}