Calomel is the name of

When a chromite ore $(A)$ is fused with sodium carbonate in free excess of air and the product is dissolved in water,a yellow solution of compound $(B)$ is obtained. After treatment of this yellow solution with sulphuric acid,compound $(C)$ can be crystallised from the solution. When compound $(C)$ is treated with $KCl$,orange crystals of compound $(D)$ crystallise out. Identify $A$ to $D$ and also explain the reactions.

Name the oxometal anions of the first series of the transition metals in which the metal exhibits the oxidation state equal to its group number.

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:

Which of the following statements are $INCORRECT$?
$A$. All the transition metals except scandium form $MO$ oxides which are ionic.
$B$. The highest oxidation number corresponding to the group number in transition metal oxides is attained in $Sc_2O_3$ to $Mn_2O_7$.
$C$. Basic character increases from $V_2O_3$ to $V_2O_4$ to $V_2O_5$.
$D$. $V_2O_4$ dissolves in acids to give $VO_4^{3-}$ salts.
$E$. $CrO$ is basic but $Cr_2O_3$ is amphoteric.
Choose the correct answer from the options given below:

Assertion : Solution of $Na_2CrO_4$ in water is intensely coloured.
Reason : Oxidation state of $Cr$ in $Na_2CrO_4$ is $+VI$.