# Which of the following is oxidized by $H_2O_2$ in the alkaline medium

$\begin{array}{1 1}(a)\;HCHO\\(b)\;Mn(II)\;salts\\(c)\;Cr(III)\;salts\\(d)\;\text{All}\end{array}$

$HCHO,Mn(II)\;salts,Cr(III)\;salts$
Hence (d) is the correct answer.