Order of acidic nature

Compare stability of free radicals

(I) $$\mathrm{CH}_3-\mathop C\limits^ \bullet H-\mathrm{CH}_3$$

(II)

(III) $$\mathop C\limits^ \bullet {H_2}-\mathrm{CH}\left(\mathrm{CH}_3\right)_2$$

(IV) $$\mathop C\limits^ \bullet {H_2}-\mathrm{CH}_3$$

(i) $$\mathrm{F}_3 \mathrm{C}-\mathrm{COOH}$$, (ii) $$\mathrm{CH}_3 \mathrm{COOH}$$, (iii) $$\mathrm{C}_6 \mathrm{H}_5 \mathrm{COOH}$$, (iv) $$\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{COOH}$$ Correct order of $$\mathrm{p} K_a$$ value is

Write IUPAC name of following compound.