The transition element of $III-B$ group which forms an alum isomorphic with $Al_2(SO_4)_3 \cdot 18H_2O$ is $Sc$. The color of the compound $Sc_2(SO_4)_3 \cdot (NH_4)_2SO_4 \cdot 24H_2O$ is:

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

Which pair of elements from the following is used to make an alloy for trophies?

Which oxide of transition metals exhibits electrical conductivity as high as that of metals?

$A$ purple colored compound of Manganese $(X)$ decomposes on heating to liberate oxygen and forms compounds of Manganese $(Y)$ and $(Z)$. Compound $(Z)$ reacts with $KOH$ in the presence of potassium nitrate to give compound $(Y)$. Compounds $(X)$,$(Y)$,and $(Z)$ respectively are:

Consider the following reactions:
$K_2Cr_2O_7$ $\xrightarrow[-H_2O]{KOH} [A]$ $\xrightarrow[-H_2O]{H_2SO_4} [B] + K_2SO_4$
The products $[A]$ and $[B]$,respectively,are: