A and B formed in the following reactions are:

$$\begin{aligned} & \mathrm{CrO}_2 \mathrm{Cl}_2+4 \mathrm{NaOH} \rightarrow \mathrm{A}+2 \mathrm{NaCl}+2 \mathrm{H}_2 \mathrm{O}, \\ & \mathrm{A}+2 \mathrm{HCl}+2 \mathrm{H}_2 \mathrm{O}_2 \rightarrow \mathrm{B}+3 \mathrm{H}_2 \mathrm{O} \end{aligned}$$

If a substance '$$A$$' dissolves in solution of a mixture of '$$B$$' and '$$C$$' with their respective number of moles as $$\mathrm{n}_{\mathrm{A}}, \mathrm{n}_{\mathrm{B}}$$ and $$\mathrm{n}_{\mathrm{C}_3}$$. Mole fraction of $$\mathrm{C}$$ in the solution is

The molecule / ion with square pyramidal shape is

Given below are two statements:

Statement - I: High concentration of strong nucleophilic reagent with secondary alkyl halides which do not have bulky substituents will follow $$\mathrm{S}_{\mathrm{N}}{ }^2$$ mechanism.

Statement - II: A secondary alkyl halide when treated with a large excess of ethanol follows $$\mathrm{S}_{\mathrm{N}}{ }^1$$ mechanism.

In the light of the above statements, choose the most appropriate from the options given below: