$Cu_2Cl_2$ with $HCl$ in the presence of oxidizing agents gives:

Guignet's green is known as

Fill in the blanks:
$(a)$ The unit of magnetic moment is ......... .
$(b)$ $Mn^{2+}$ has .......... color.
$(c)$ $Fe_3H$ is a ............. type of compound.

The addition of metals like $Cr$,$Mn$,$W$ and $Ni$ to ordinary steel makes it

The purple colour of $KMnO_4$ is due to the transition:

$K_2Cr_2O_7 + H_2O_2 \xrightarrow{H^{+}} $