The decreasing order of the acidic character of the following is-

(A) $\left( I \right) > \left( {II} \right) > \left( {III} \right) > \left( {IV} \right)$
(B) $\left( I \right) > \left( {III} \right) > \left( {II} \right) > \left( {IV} \right)$
(C) $\left( {IV} \right) > \left( {III} \right) > \left( {II} \right) > \left( I \right)$
(D) $\left( {IV} \right) > \left( {II} \right) > \left( {III} \right) > \left( I \right)$

Hint: The acid strength refers to the acid 's ability to dissociate into a proton, H+, and anion, A−, symbolized by the chemical shape, HA. With the exception of the most concentrated solutions, the dissociation of a strong acid is always complete.
Complete step by step solution:
> It is a strong acid that ionizes completely in a solution while a weak acid ionizes only partially. Strong acids in the ecosystem are corrosive and cause serious skin burns. Moreover, the weak acids are just mildly corrosive, except in our food and body. Strong acids have examples such as hydrochloric acid and sulphuric acid. A few examples of weak acids are ethanoic acid, acid citric (citric fruits) and acetic acid (vinegar).
> The stronger acid is an acid of a larger degree of dissociation. Let us now understand the factors that depend on the strength of an acid. The degree of acid dissociation depends on two factors: H-A bond strength and H-A bond polarity.
- There are more acidic cycloalkanes than the alkanes concerned.
- The most acidic of cyclopropane, and the least acidic of n butane.
In general, alkanes are inert to acids and bases because of their non-polar nature and their inability to give or receive electrons. C-C and C-H bonds.

Hence, it is clear that option B is the correct option.

Note: The acid is typically stronger if the strength of the H-A bond is weak. Likewise, the stronger is the acid, the greater the H-A bonding polarity. The dissociation of acid molecules into H+ and A- is thus simpler with these variables.