When a mixture of manganese dioxide,potassium hydroxide and potassium chlorate is fused,the product obtained is

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:

The transition metal ions responsible for colour in ruby and emerald are,respectively:

When acidified $K_2Cr_2O_7$ reacts with $H_2O_2$,a blue-coloured solution is obtained. This blue colour is due to the formation of:

$KMnO_4$ is the oxo-salt of the acid of which of the following oxides?

In the dichromate dianion $(Cr_2O_7^{2-})$,which of the following statements is correct regarding the $Cr-O$ bonds?