$A$ 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?

$A$ gas can be taken from state $A$ to state $B$ via two different paths $ACB$ and $ADB$. When path $ACB$ is used, $60 \text{ J}$ of heat flows into the system and $30 \text{ J}$ of work is done by the system. If path $ADB$ is used, the work done by the system is $10 \text{ J}$. The heat flow into the system in path $ADB$ is: (in $text{ J}$)

For the gaseous reaction,$N_2O_4(g) \to 2NO_2(g)$,which of the following relations is correct?

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

Which of the following is the correct mathematical expression for the first law of thermodynamics?

$A$ system performs mechanical work equal to $15 \ kJ$ and loses $2 \ kJ$ of heat to the surroundings. What is the change in internal energy of the system (in $kJ$)?