Which pair of elements has the same chemical properties?

Given below are two statements:
Statement $I$: Chlorine can easily combine with oxygen to form oxides,and the product has a tendency to explode.
Statement $II$: Chemical reactivity of an element can be determined by its reaction with oxygen and halogens.
In the light of the above statements,choose the correct answer from the options given below.

Which of the following elements with the given electronic configurations belong to the same group?
$(i)$ $1s^2 2s^2$
$(ii)$ $1s^2 2s^2 2p^5$
$(iii)$ $1s^2 2s^2 2p^6 3s^2 3p^5$
$(iv)$ $1s^2 2s^2 2p^6 3d^{10} 4s^1$

Why do elements in the same group have similar physical and chemical properties?

Which of the following has the maximum tendency for hydrate formation?

Regarding $F^{-}$ and $Cl^{-}$,which of the following statements is/are correct?
$(i)$ $Cl^{-}$ can give up an electron more easily than $F^{-}$
$(ii)$ $Cl^{-}$ is a better reducing agent than $F^{-}$
$(iii)$ $Cl^{-}$ is smaller in size than $F^{-}$
$(iv)$ $F^{-}$ can be oxidized more readily than $Cl^{-}$