Consider the following reaction approaching equilibrium at 27$^\circ$C and 1 atm pressure

$\mathrm{A+B}$ $\mathrel{\mathop{\kern0pt\rightleftharpoons} \limits_{{k_r} = {{10}^2}}^{{k_f} = {{10}^3}}}$ $\mathrm{C+D}$

The standard Gibb's energy change $\mathrm{(\Delta_r G^\theta)}$ at 27$^\circ$C is ($-$) ___________ kJ mol$^{-1}$ (Nearest integer).

(Given : $\mathrm{R=8.3~J~K^{-1}~mol^{-1}}$ and $\mathrm{\ln 10=2.3}$)