Write the uses of fluorine.
 

$\mathrm{F}$-atom is more electronegative than $\mathrm{I}$-atom, yet $\mathrm{HF}$ has lower acid strength than $\mathrm{HI}$. Why?

${\mathrm{ClF}}_3$ exists but ${\mathrm{FCl}}_3$ does not exist. Why?

Statement I: Acid strength increases in the order given as

$\mathrm{HF}<<\mathrm{HCl}<<\mathrm{HBr}<<\mathrm{HI}$

Statement II:
As the size of the elements $\mathrm{F}, \mathrm{Cl}, \mathrm{Br}, \mathrm{I}$ increases down the group, the bond strength of $\mathrm{HF}, \mathrm{HCl}$ $\mathrm{HBr}$ and HI decreases and so the acid strength increases.

In the light of the above statements, choose the correct answer from the options given below.