Given below are two statements :

Statement I : The number of species among $\mathrm{BF}_4^{-}, \mathrm{SiF}_4, \mathrm{XeF}_4$ and $\mathrm{SF}_4$, that have unequal $\mathrm{E}-\mathrm{F}$ bond lengths is two. Here, E is the central atom.

Statement II : Among $\mathrm{O}_2^{-}, \mathrm{O}_2^{2-}, \mathrm{F}_2$ and $\mathrm{O}_2^{+}, \mathrm{O}_2^{-}$has the highest bond order.

In the light of the above statements, choose the correct answer from the options given below

Consider the following redox reaction taking place in acidic medium

$$ \mathrm{BH}_4^{-}(a q)+\mathrm{ClO}_3^{-}(a q) \longrightarrow \mathrm{H}_2 \mathrm{BO}_3^{-}(a q)+\mathrm{Cl}^{-}(a q) $$

If the Nernst equation for the above balanced reaction is

$$ \mathrm{E}_{\mathrm{cell}}=\mathrm{E}_{\mathrm{cell}}^{\circ}-\frac{\mathrm{RT}}{\mathrm{nF}} \ln \mathrm{Q}, $$

then the value of $n$ is $\_\_\_\_$ .(Nearest integer)

X is the number of geometrical isomers exhibited by $\left[\mathrm{Pt}\left(\mathrm{NH}_3\right)\left(\mathrm{H}_2 \mathrm{O}\right) \mathrm{BrCl}\right]$.

Y is the number of optically inactive isomer(s) exhibited by $\left[\mathrm{CrCl}_2(\mathrm{ox})_2\right]^{3-}$

Z is the number of geometrical isomers exhibited by $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_3\left(\mathrm{NO}_2\right)_3\right]$.

The value of $\mathrm{X}+\mathrm{Y}+\mathrm{Z}$ is $\_\_\_\_$ .

Consider the dissociation equilibrium of the following weak acid

$$ \mathrm{HA} \rightleftharpoons \mathrm{H}^{+}(\mathrm{aq})+\mathrm{A}^{-}(\mathrm{aq}) $$

If the pKa of the acid is 4 , then the pH of 10 mM HA solution is $\_\_\_\_$ .(Nearest integer)

[Given: The degree of dissociation can be neglected with respect to unity]