Answer
$Cu^{2+} < O_{2} < Cr_{2}O_{7}^{2-} < Cl_{2} < H_{2}O_{2}$
Work Step by Step
Oxidizing strengths of each are given below:
$Cr_{2}O_{7}^{2-}: +1.33$
$H_{2}O_{2}: +1.776$
$Cu^{2+}: 0.337$
$Cl_{2}: +1.359%$
$O_{2}: +1.23$
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