Potassium manganate $(K_2MnO_4)$ is not formed in which of the following reactions?

Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing $pH$ on a solution of potassium dichromate?

Correct statements from the following are:
$A$. Potassium dichromate is an oxidising agent and it oxidises $FeSO_4$ to $Fe_2(SO_4)_3$ in acidic medium.
$B$. Sodium dichromate can be used as primary standard in volumetric estimation.
$C$. $CrO_4^{2-}$ and $Cr_2O_7^{2-}$ are interconvertible in aqueous solution by varying the $pH$ of the solution.
$D$. $Cr-O-Cr$ bond angle in $Cr_2O_7^{2-}$ is $126^\circ$.
Choose the correct answer from the options given below:

Match the aqueous solutions given in List-$I$ with their colors given in List-$II$:

List-$I$ (Aqueous solution of salt)	List-$II$ (Color)
$A$. $FeSO_4 \cdot 7H_2O$	$i$. Green
$B$. $NiCl_2 \cdot 4H_2O$	$ii$. Pale pink
$C$. $MnCl_2 \cdot 4H_2O$	$iii$. Blue
$D$. $CoCl_2 \cdot 6H_2O$	$iv$. Light green
$E$. $Cu_2Cl_2$	$v$. Pink
	$vi$. Colorless

Which from the following is the general formula of the compound obtained when lanthanoid $(Ln)$ reacts with carbon at elevated temperature?

When a mixture of potassium dichromate and potassium chloride is heated with concentrated $H_2SO_4$,which of the following is produced as red vapors?