When a manganese $(Mn^{II})$ salt is fused with a mixture of $KNO_3$ and solid $NaOH$,what will be the oxidation state of $Mn$ after it changes from $+2$?

Boiling $CuCl_2$ with $Cu$ in concentrated $HCl$ gives:

In a borax bead test under hot condition,a metal salt is heated at point $B$ of the flame,resulting in a green-coloured salt bead. The spin-only magnetic moment value of the salt is $..........$ $BM$ (Nearest integer). [Given atomic number of $Cu=29, Ni=28, Mn=25, Fe=26$]

The products $A$ and $B$ formed in the following reactions are:
$CrO_2Cl_2 + 4NaOH \rightarrow A + 2NaCl + 2H_2O$
$A + 2HCl + 2H_2O_2 \rightarrow B + 3H_2O$

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

When $Cu^{2+}$ ion is treated with $KI$,a white precipitate,$X$ appears in solution. The solution is titrated with sodium thiosulphate,the compound $Y$ is formed. $X$ and $Y$ respectively are