What is the correct order of acidity of the protons marked $A–D$ in the given compounds?

 

The most stable carbocation for the following is:

Match List I with List II:

Match items of column I and II

A solution of ${\mathrm{FeCl}}_3$ when treated with ${\mathrm{K}}_4\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]$ gives a prussian blue precipitate due to the formation of

Number of isomeric compounds with molecular formula ${\mathrm{C}}_9{\mathrm{H}}_{10}\mathrm{O}$ which

(i) do not dissolve in $\mathrm{NaOH}$
(ii) do not dissolve in $\mathrm{HCl}$.

(iii) do not give orange precipitate with $2,4$ - DNP

(iv) on hydrogenation give identical compound with molecular formula ${\mathrm{C}}_9{\mathrm{H}}_{12}\mathrm{O}$ is