Consider the following electrochemical cell at standard condition. Au ( s )| QH_2, Q | NH_4 X (0.01 M )| | Ag^+(1 M ) ∣ Ag ( s ) E_cell =+0.4 V The…

Consider the following electrochemical cell at standard condition. $\displaystyle \mathrm{Au}(\mathrm{s})\left|\mathrm{QH}_2, \mathrm{Q}\right| \mathrm{NH}_4 \mathrm{X}(0.01 \mathrm{M})| | \mathrm{Ag}^{+}(1 \mathrm{M}) \mid \mathrm{Ag}(\mathrm{s}) \mathrm{E}_{\text {cell }}=+0.4 \mathrm{~V}$ The couple $\displaystyle \mathrm{QH}_2 / \mathrm{Q}$ represents quinhydrone electrode, the half cell reaction is given below : [Given : $\displaystyle \mathrm{E}_{\mathrm{Ag}^{+} / \mathrm{Ag}}^{\circ}=+0.8 \mathrm{~V}$ and $\displaystyle \frac{2.303 \mathrm{RT}}{\mathrm{F}}=0.06 \mathrm{~V}$ ] The $\displaystyle \mathrm{pK}_{\mathrm{b}}$ value of the ammonium halide salt $\displaystyle \left(\mathrm{NH}_4 \mathrm{X}\right)$ used here is $\displaystyle \_\_\_\_$. (nearest integer)