Three moles of an ideal gas expanded spontaneously into vacuum. The work done will be .............. $Joules$.

Which statement is correct?

In the equation $C_P - C_V = R$,what does $R$ represent?

One mole of an ideal gas at $300 \ K$ is expanded isothermally from an initial volume of $1 \ L$ to $10 \ L$. The value of $\Delta E$ for this process is $(R = 2 \ cal \ mol^{-1} \ K^{-1})$.

$A$ certain mass of a gas was brought from state $A$ to $B$ by following three different paths,namely $1$,$2$ and $3$,respectively. Which of the following relations is correct for the work done?

Find the constant external pressure required to expand a gas from $2.5 \ L$ to $4.5 \ L$ if the amount of work done is $500 \ J$ at $298 \ K$. (in $bar$)