When a system is taken from state $i$ to state $f$ along the path $iaf$,$Q = 50 \ J$ and $W = 20 \ J$. Along the path $ibf$,$Q = 35 \ J$ and $W = -13 \ J$. For the curved path $fi$,$Q = \dots \ J$.

An engineer claims to have built an engine that delivers $10 \, kW$ of power with a fuel consumption of $1 \, g/s$. If the calorific value of the fuel is $2 \, kcal/g$, is the engineer's claim valid?

$A$ gas undergoes a change of state during which $100 \ J$ of heat is supplied to it and it does $20 \ J$ of work. The system is brought back to its original state through a process during which $20 \ J$ of heat is released by the gas. The work done by the gas in the second process is ....... $J$

An engineer claims to have made an engine delivering $10 \, kW$ power with fuel consumption of $1 \, g \, s^{-1}$. The calorific value of the fuel is $2 \, kcal \, g^{-1}$. His claim:

Two gases have the same initial pressure,volume,and temperature. They expand to the same final volume,one adiabatically and the other isothermally.

$A$ sample of an ideal gas is taken through the cyclic process $ABCA$ as shown in the figure. It absorbs $40 \ J$ of heat during the part $AB$,no heat during $BC$,and rejects $60 \ J$ of heat during $CA$. $A$ work of $50 \ J$ is done on the gas during the part $BC$. The internal energy of the gas at $A$ is $1560 \ J$. The work done by the gas during the part $CA$ is.............$J$.