$FeSO_4 \cdot 7H_2O$ (Green Vitriol) salt on thermal decomposition does not produce

Which Lanthanoid compound is used as a pigment?

To support the tungsten filament in an electric bulb,the metal used is:

Identify correct statements from below:
$A$. The chromate ion is square planar.
$B$. Dichromates are generally prepared from chromates.
$C$. The green manganate ion is diamagnetic.
$D$. Dark green coloured $K_2MnO_4$ disproportionates in a neutral or acidic medium to give permanganate.
$E$. With increasing oxidation number of transition metal,ionic character of the oxides decreases.
Choose the correct answer from the options given below:

Which oxide of manganese is amphoteric in nature?

Identify the correct $(T)$ and incorrect $(F)$ statements from the following:
$(a)$ $MnO_4^{2-}$ is diamagnetic.
$(b)$ $MnO_4^-$ is green and $MnO_4^{2-}$ is purple.
$(c)$ $K_2Cr_2O_7$ is yellow.
$(d)$ $K_2Cr_2O_7$ is orange.