Consider the following reversible reaction, $$A\left( g \right) + B\left( g \right) \to AB\left( g \right).$$

The activation energy of the backward reaction exceeds that of the forward reaction by $$2RT$$ (in $$J\,mo{l^{ - 1}}$$). If the pre-exponential factor of the forward reaction is $$4$$ times that of the reverse reaction, the absolute value of $$\Delta {G^ \circ }$$ (in $$J\,mo{l^{ - 1}}$$ ) for the reaction at $$300$$ $$K$$ is ____________.

(Given; $$\ln \left( 2 \right) = 0.7,RT = 2500$$ $$J\,mo{l^{ - 1}}$$ at $$300$$ $$K$$ and $$G$$ is the Gibbs energy)

Aniline reacts with mixed acid (conc. $$HN{O_3}$$ and conc. $${H_2}S{O_4}$$) at $$288$$ $$K$$ to give P $$\left( {51\% } \right),$$ Q $$\left( {47\% } \right)$$ and R $$\left( {2\% } \right).$$ The major product(s) of the following reaction sequence is (are)

For the given compound $$X,$$ the total number of optically active stereoisomers is ____________.

The correct option(s) regarding the complex

$${\left[ {Co\left( {en} \right){{\left( {N{H_3}} \right)}_3}\left( {{H_2}O} \right)} \right]^{3 + }}\,\,$$ $$\left( {en = {H_2}NC{H_2}C{H_2}N{H_2}} \right)$$ is (are)