A 3KW electric resistance heater submerged in 2.5kg water is turned on and left on for 5 min. During the process ,150KJ of heat is lost from the water . The final temperature of water(in ºC) if the initial temperature of water is 40ºC.

Explain why (a) Two bodies at different temperatures $T_1$ and $T_2$ if brought in thermal contact do not necessarily settle to the mean temperature $(T_1 + T_2)/2$.

What amount of heat must be supplied to $2.0 \times 10^{-2}$ kg of nitrogen (at room temperature) to raise its temperature by $45^\circ C$ at constant pressure ? (Molecular mass of $N_2 = 28$; $R = 8.3 J mol^{-1} K^{-1}$.)

Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Answer the following : (a) What is the final pressure of the gas in A and B ?

Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Answer the following : (b) What is the change in internal energy of the gas ?

A refrigerator is to maintain eatables kept inside at $9^\circ C$. If room temperature is $36^\circ C$, calculate the coefficient of performance.

Explain why (d) The climate of a harbour town is more temperate than that of a town in a desert at the same latitude.

A thermodynamic system is taken from an original state to an intermediate state by the linear process shown in Fig. (12.13). 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.

Explain why (b) The coolant in a chemical or a nuclear plant (i.e., the liquid used to prevent the different parts of a plant from getting too hot) should have high specific heat.

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

Explain why (c) Air pressure in a car tyre increases during driving.

Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Answer the following : (c) What is the change in the temperature of the gas ?

A steam engine delivers $5.4 \times 10^8 J$ of work per minute and services $3.6 \times 10^9 J$ of heat per minute from its boiler. What is the efficiency of the engine? How much heat is wasted per minute?

Energy is recieved by a solar collector at the rate of 300KW from a source temperatureof 2400 K . If 60KW of this energy is lost to the surrounding at steady state and if the user temperature remains constant at 600 K , what are the first law and second law efficiencies .(Take temperature of surrounding as 300 K)

Two cylinders A and B of equal capacity are connected to each other via a stopcock. A contains a gas at standard temperature and pressure. B is completely evacuated. The entire system is thermally insulated. The stopcock is suddenly opened. Answer the following : (d) Do the intermediate states of the system (before settling to the final equilibrium state) lie on its P-V-T surface ?

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

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 cal = 4.19 J)

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 ?