$\begin{array}{1 1} (1) Cl^{−}\; and\; ClO^{−} \\ (2) Cl^{−}\; and\; ClO^{-}_2 \\ (3) ClO− and ClO_3^{-} \\ (4) ClO_2^{−}\; and\;ClO^{-}_3 \end{array} $