Which of the following elements is the most basic?

Which of the following represents the correct order for oxidising power of the given species $ClO_4^{-}$,$BrO_4^{-}$,and $IO_4^{-}$?

State the occurrence of group-$17$ elements.

An inorganic white crystalline compound $(A)$ has a rock salt structure. $(A)$ on reaction with conc. $H_2SO_4$ and $MnO_2$ evolves a pungent smelling,greenish-yellow gas $(B)$. Compound $(A)$ gives a white precipitate of $(C)$ with $AgNO_3$ solution. Compounds $(A)$,$(B)$,and $(C)$ will be respectively:

Chlorine reacts with hot and concentrated $NaOH$ and produces compounds $(X)$ and $(Y)$. Compound $(X)$ gives a white precipitate with silver nitrate solution. The average bond order between $Cl$ and $O$ atoms in $(Y)$ is

The bleaching action of chlorine is due to $....................$.