The blue borax bead is obtained by which of the following?

Provide the structures for:
$1.$ $MnO_4^{-}$
$2.$ $MnO_4^{2-}$

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

What is the color of $K_2MnO_4$?

$X$ is an oxoanion of the lightest element of group $7$ in the periodic table. The metal is in $+6$ oxidation state in $X$. The color of the potassium salt of $X$ is

The yellow colour solution of $Na_2CrO_4$ changes to orange-red on passing $CO_2$ gas due to the formation of $:-$