The colour of $K_2Cr_2O_7$ changes from red-orange to lemon-yellow on treatment with aqueous $KOH$ because of:

Which of the following statements regarding copper salts is not true?

Consider the following reactions:
$K_2Cr_2O_7 + NaCl + H_2SO_4 \rightarrow CrO_2Cl_2 + \text{Side Products}$
$CrO_2Cl_{2(Vapour)} + NaOH \rightarrow B + NaCl + H_2O$
$B + H^+ \rightarrow C + H_2O$
The number of terminal $'O'$ atoms present in the compound $'C'$ is $..........$

Which of the following substances will not give the borax bead test?

For $Cu_{2}Cl_{2}$ and $CuCl_{2}$ in aqueous medium,which of the following statements is correct?

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: