The work done when $2 \, mol$ of an ideal gas expands from $5 \, L$ to $15 \, L$ at a temperature of $300 \, K$ is .............. $kJ$.

The internal energy change when a system goes from state $A$ to $B$ is $40 \, kJ/mol$. If the system goes from $A$ to $B$ by a reversible path and returns to state $A$ by an irreversible path,what would be the net change in internal energy?

What is the enthalpy change (in $J$) for converting $9 \ g$ of $H_2O(l)$ at $+10^{\circ}C$ to $H_2O(l)$ at $+20^{\circ}C$? $(C_p(H_2O(l)) = 75 \ J \ mol^{-1} \ K^{-1})$

Prove that the change in enthalpy of a system in which a chemical reaction occurs is equal to the heat gained by the system at constant pressure.

It is a general principle that the less energy a system contains,it is:

An ideal gas is allowed to expand against a constant pressure of $2 \ bar$ from $10 \ L$ to $50 \ L$ in one step. Calculate the amount of work done by the gas. If the same expansion were carried out reversibly,will the work done be higher or lower than the earlier case? (Given that $1 \ L \ bar = 100 \ J$)