For a system at equilibrium,$\Delta G = 0$ under which of the following conditions?

At $298 \ K$,if the standard Gibbs energy change $\Delta_r G^{\ominus}$ of a reaction is $-115 \ kJ \ mol^{-1}$,the value of $\log_{10} K_{p}$ will be $(R = 8.314 \ J \ K^{-1} \ mol^{-1})$.

The equilibrium concentrations of the species in the reaction $A + B \rightleftharpoons C + D$ are $3, 5, 10$ and $15 \ mol \ L^{-1}$ respectively at $300 \ K$. The $\Delta G$ for the reaction is (in $cal$)

Which of the following relations is incorrect?

The correct relationship between the standard Gibbs free energy change $(\Delta G^o)$ and the equilibrium constant $(K_c)$ for a reaction is .......

Find out the value of the equilibrium constant for the following reaction at $298 \, K$.
$2 NH_{3(g)} + CO_{2(g)} \leftrightharpoons NH_{2}CONH_{2(aq)} + H_{2}O_{(l)}$
Standard Gibbs energy change,$\Delta_{r} G^{\ominus}$ at the given temperature is $-13.6 \, kJ \, mol^{-1}$.