$A$ thermodynamic system absorbs $2 \, kcal$ of heat and performs $500 \, J$ of work. The change in its internal energy is ......... $J$.

$A$ gas is supplied with $1500 \; J$ of heat energy at constant pressure. If the constant pressure of the gas is $2.1 \times 10^{5} \; N/m^{2}$ and the increase in volume is $2.5 \times 10^{-3} \; m^{3}$,then the increase in the internal energy of the gas is ...... $J$.

If $Q$,$E$,and $W$ denote respectively the heat added,change in internal energy,and the work done by a closed cycle process,then

When a system is taken from thermodynamic state $i$ to $f$ along the path $iaf$ (see figure),it is found that the heat $Q$ absorbed by the system is $50 \ cal$ and the work $W$ done by the system is $20 \ cal$. Along the path $ibf$,$Q = 36 \ cal$. What is the work $W$ done along the path $ibf$ (in $cal$)?

The first law of thermodynamics states that:

When $150 \ J$ of heat is supplied to a system,the work done by the system is $110 \ J$. The change in the internal energy of the system is ....... $J$.