Which of the following is the strongest acid?

Which of the following statements regarding the properties of halogens are correct?
$(a)$ Due to small size and strong inter-electronic repulsion,the electron gain enthalpy of fluorine is less negative than that of chlorine.
$(b)$ Iodine has a different physical state and colour compared to other members of the group.
$(c)$ Fluorine does not show a positive oxidation state.
$(d)$ In $X_{2(g)} + H_2O(l) \rightarrow HX(aq) + HOX(aq)$ (where $X = Cl$ or $Br$).

Which halogen does not show variable oxidation state?

Consider the following reactions :
$(i)$ $F_2 + 2X^{-} \to 2F^{-} + X_2$ $(X = Cl, Br, I)$
$(ii)$ $Cl_2 + 2X^{-} \to 2Cl^{-} + X_2$ $(X = Br, I)$
$(iii)$ $I_2 + 2Br^{-} \to 2I^{-} + Br_2$
Which option has only the correct set of reactions?

How can you prepare $Cl_2$ from $HCl$ and $HCl$ from $Cl_2$? Write reactions only.

Which of the following substances is used to prepare $UF_6$ during the enrichment process of ${}_{92}U^{235}$?