Which of the following carbonium ion is not most stable

${\mathrm{pK}}_{\mathrm{a}}$ value of the compound decreases if $\mathrm{X}$ is

(Major): Here $\mathrm{A}$ is

The ${\mathrm{K}}_{\mathrm{a}}$ values of alcohols, water and phenol are of order ${10}^{-17}, {10}^{-14}$ and ${10}^{-10}$ respectively. Which of the following reactions is possible

(I) ${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{O}}^{⊝}+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{C}}_6{\mathrm{H}}_5\mathrm{OH}+{\mathrm{OH}}^{⊝}$

(II) ${\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{O}}^{⊝}+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}+{\mathrm{OH}}^{⊝}$

Stability of:

(I) 

(II) 

(III) 

(IV)

in the increasing order is:

What will be the correct order of stability of following carbocations:

(I) 

(II)

(III)

(IV)