NCERT Solutions

11.1 A geyser heats water flowing at the rate of 3.0 litres per minute from $27^{\circ} \mathrm{C}$ to $77^{\circ} \mathrm{C}$. If the geyser operates on a gas burner, what is the rate of consumption of the fuel if its heat of combustion is $4.0 \times 10^{4} \mathrm{~J} / \mathrm{g}$ ?

11.2 What amount of heat must be supplied to $2.0 \times 10^{-2} \mathrm{~kg}$ of nitrogen (at room temperature) to raise its temperature by $45{ }^{\circ} \mathrm{C}$ at constant pressure ? (Molecular mass of $\mathrm{N}_{2}=28 ; R=8.3 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$.)

11.4 A cylinder with a movable piston contains 3 moles of hydrogen at standard temperature and pressure. The walls of the cylinder are made of a heat insulator, and the piston is insulated by having a pile of sand on it. By what factor does the pressure of the gas increase if the gas is compressed to half its original volume ?

11.5 In changing the state of a gas adiabatically from an equilibrium state $A$ to another equilibrium state $B$, an amount of work equal to 22.3 J is done on the system. If the gas is taken from state $A$ to $B$ via a process in which the net heat absorbed by the system is 9.35 cal , how much is the net work done by the system in the latter case ? (Take $1 \mathrm{cal}=4.19 \mathrm{~J}$ )

11.7 An electric heater supplies heat to a system at a rate of 100 W . If system performs work at a rate of 75 joules per second. At what rate is the internal energy increasing?

11.8 A thermodynamic system is taken from an original state to an intermediate state by the linear process shown in Fig. (11.11)

[Image: A P-V diagram showing a process from state D to E to F. State D is at (V=2, P=600). State E is at (V=5, P=300). State F is at (V=2, P=300). The path from D to E is a straight line. The path from E to F is a horizontal line (isobaric).]

Its volume is then reduced to the original value from E to F by an isobaric process. Calculate the total work done by the gas from D to E to F