Question

Which one of the following reactions does not occur?

• A. $F _{2}+2 Cl ^{-} \longrightarrow 2 F ^{-}+ Cl _{2}$
• B. $Cl _{2}+2 F ^{-} \longrightarrow 2 Cl ^{-}+ F _{2}$
• C. $Br _{2}+2 I ^{-} \longrightarrow 2 Br ^{-}+ I _{2}$
• D. $Cl _{2}+2 Br ^{-} \longrightarrow 2 Cl ^{-}+ Br _{2}$

Answer 1

Answer: (C)

With progressive increase in atomic number, the reduction potential of halogens decreases, thus oxidising power also decreases. Hence, a halogen with lower atomic number will oxidise the halide ion of higher atomic number and therefore, will liberate them from their salt solution.
Hence, the reaction
$Cl _{2}+2 F ^{-} \longrightarrow 2 Cl ^{-}+ F _{2}$
is not possible.