In ...... process,work is done at the expense of internal energy.

$A$ gas expands isothermally from $10 \, dm^3$ to $20 \, dm^3$ at a constant external pressure of $1 \, atm$. If it absorbs $800 \, J$ of heat from the surroundings,what is the value of $\Delta U$ in $J$ for this process?

The first law of thermodynamics for an isothermal process is:

$A$ certain mass of an ideal gas absorbs $80 \ kJ$ heat and the gas is expanded from $2 \ L$ to $10 \ L$ at a constant pressure of $25 \ bar$. What is $\Delta U$ for the gas in the process in $kJ$? $(1 \ bar-L = 100 \ J)$

For an isothermal reversible expansion process,the value of $q$ can be calculated by the expression

$A$ gas undergoes a change from state $A$ to state $B$. In this process,the heat absorbed and work done by the gas are $5\, J$ and $8\, J$,respectively. Now,the gas is brought back to $A$ by another process during which $3\, J$ of heat is evolved. In this reverse process of $B$ to $A$: