For the given compounds, the correct order of increasing $$\mathrm{pK}_{\mathrm{a}}$$ value :

Choose the correct answer from the options given below :

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : Both rhombic and monoclinic sulphur exist as $$\mathrm{S}_8$$ while oxygen exists as $$\mathrm{O}_2$$.

Reason (R) : Oxygen forms $$p \pi-p \pi$$ multiple bonds with itself and other elements having small size and high electronegativity like $$\mathrm{C}, \mathrm{N}$$, which is not possible for sulphur.

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

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): The total number of geometrical isomers shown by $$[\mathrm{Co}(\mathrm{en})_2 \mathrm{Cl}_2]^{+}$$ complex ion is three.

Reason (R): $$[\mathrm{Co}(\mathrm{en})_2 \mathrm{Cl}_2]^{+}$$ complex ion has an octahedral geometry.

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

Methods used for purification of organic compounds are based on :