Potassium dichromate when heated with concentrated sulphuric acid and a soluble chloride,gives brown-red vapours of:

Which of the following is the green coloured powder produced when ammonium dichromate is used in fireworks?

If an oxide of manganese has a value of magnetic moment $( \mu )$ of $4.9 \ BM$,then which oxide would it be?

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:

Corundum is

When $XO_2$ is fused with an alkali metal hydroxide in the presence of an oxidizing agent such as $KNO_3$,a dark green product is formed which disproportionates in an acidic solution to afford a dark purple solution. $X$ is