The green paramagnetic species formed by heating $KMnO_4$ at $513 \ K$ is

The pair of compounds in which both the metals are in the highest possible oxidation state is

The false statement about iron $(III)$ hydroxide is that

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 of the following is a highly corrosive salt?

When a small amount of vanadium is added to steel,it becomes: