1-pentyne(A) is treated with $4N$ alcoholic $KOH$ at $175^{\circ}C$. It is converted slowly into an equilibrium mixture of $1.3 \% \: 1-$ pentyne, $95.2 \%\: 2$-pentyne(B) and $3.5 \%$ of $1,2-$ pentadiene(C). The equilibrium was maintained at $175^{\circ}C. $ \[\] Calculate $ \Delta G^{\circ}$ for the equilibrium \[\] $B \leftrightharpoons C$