91Ó°ÊÓ

Caesium is electropositive having an oxidation state of +1 and gives${\mathbf{Cs}}^{\mathbf{+}}$cation.

Bromine is electronegative having an oxidation state of -1 and gives ${\mathbf{Br}}^{\mathbf{-}}$anion.

Thus, their oxidation states get exchanged and form caesium bromide having formula,CsBr.

Barium is electropositive having an oxidation state of +2 and gives ${\mathbf{Ba}}^{\mathbf{2}\mathbf{+}}$cation.

Sulphur is electronegative having an oxidation state of -2 as ${\mathbf{S}}^{\mathbf{2}\mathbf{-}}$an anion.

Thus, their oxidation states get exchanged and form barium sulphide having formula BaS.

Calcium is electropositive having an oxidation state of +2 and gives ${\mathbf{Ca}}^{\mathbf{2}\mathbf{+}}$cation.

Fluorine is electronegative having an oxidation state of -1 as ${\mathbf{F}}^{\mathbf{-}}$an anion.

Thus, their oxidation states get exchanged and form a calcium fluoride having formula ${\mathbf{CaF}}_{\mathbf{2}}$.