The covalent radii of atoms $A$ and $B$ are $r_A$ and $r_B$, respectively. The covalent bond length and total length of AB molecule are respectively

Consider the following data for the reaction

$$ X_2(g)+Y_2(g) \rightleftharpoons 2 X Y(g) $$

at $600 \mathrm{~K}^{\circ}$. The $\Delta_{\mathrm{r}} \mathrm{G}^{\ominus}$ (in $\mathrm{kJ} \mathrm{mol}^{-1}$ ) for the reaction is :

$$ \begin{array}{|c|c|c|} \hline \text { Compound } & \Delta_f \mathrm{H}_{600 \mathrm{~K}}^{\ominus}\left(\mathrm{kJ} \mathrm{~mol}^{-1}\right) & \mathrm{S}^{\ominus}{ }_{600 \mathrm{~K}}\left(\mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}\right) \\ \hline \mathrm{XY}(\mathrm{~g}) & 42 & 200 \\ \hline \mathrm{X}_2(\mathrm{~g}) & 8 & 140 \\ \hline \mathrm{Y}_2(\mathrm{~g}) & 80 & 250 \\ \hline \end{array} $$

The correct order of molar heat capacities measured at 298 K and 1 bar is :

The reaction $\mathrm{A}(\mathrm{g}) \rightleftharpoons \mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})$ was initiated with the amount ' a ' of $\mathrm{A}(\mathrm{g})$. At equilibrium it is found that the amount of $\mathrm{A}(\mathrm{g})$ remaining is ( $\mathrm{a}-x$ ) at a total pressure of p .

The equilibrium constant Kp of the reaction can be calculated from the expression :