When a system is supplied with $60 \ J$ of heat,it performs $15 \ J$ of work. The change in the internal energy of the system is ......... $J$.

For the reaction $3O_{2(g)} \rightarrow 2O_{3(g)}$,the value of $\Delta U - \Delta H$ is equal to .....

According to the first law of thermodynamics,which of the following is correct? (Where $q =$ heat supplied to the system and $W =$ work done by the system)

Assertion : For an isothermal reversible process $Q = -W$,i.e.,work done by the system equals the heat absorbed by the system.
Reason : Enthalpy change $(\Delta H)$ is zero for an isothermal process.

Based on the first law of thermodynamics,which of the following is correct?

If the internal energy of an ideal gas decreases by the same amount of the work done by the system,the process is