$A$ system is changed from state $A$ to state $B$ by one path and from $B$ to $A$ by another path. If $E_1$ and $E_2$ are the corresponding changes in internal energy,then:

Which of the following processes involves zero work done?

Which among the following is true for the reactions involving only solids or liquids?

At $T(K)$, $2 \ mol$ of an ideal gas is allowed to expand reversibly and isothermally from a pressure of $10 \ atm$ to $1 \ atm$. The work done (in $kJ$) is $(R=8.3 \ J \ K^{-1} \ mol^{-1})$.

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 $\log 2 = 0.3010$)

Which of the following is an extensive property of a system?