Which of the following is a path function?

$A$ gas is allowed to expand against a constant external pressure of $2.5 \ bar$ from an initial volume of $2.5 \ L$ to a final volume of $4.5 \ L$. What is the amount of work done (in $J$)?

Which of the following are extensive properties?
$(A)$ Heat capacity
$(B)$ Entropy
$(C)$ Gibbs' energy
$(D)$ Concentration
$(E)$ Vapour pressure

The difference between $C_p$ and $C_v$ can be derived using the empirical relation $H = U + PV$. Calculate the difference between $C_p$ and $C_v$ for $10$ moles of an ideal gas.

When $5 \ mol$ of $He$ gas expand isothermally and reversibly at $300 \ K$ from $10 \ L$ to $20 \ L,$ the magnitude of the maximum work obtained is $....... \ J$. [nearest integer] (Given: $R = 8.3 \ J \ K^{-1} \ mol^{-1}$ and $\log 2 = 0.3010$)

During the reversible isothermal expansion of an ideal gas,the change in internal energy is......