In mildly alkaline medium,thiosulphate ion is oxidized by $MnO_4^-$ to $A$. The oxidation state of sulphur in $A$ is ..... .

Write the balanced chemical equations for the following reactions:
$(1)$ Reaction between $MnO_4^-$ and $I^-$ in neutral or faintly alkaline solution.
$(2)$ Reaction between $MnO_4^-$ and $C_2O_4^{2-}$ in acidic medium $(H^+)$.

How many moles of $K_2Cr_2O_7$ can be reduced by $1 \ mol$ of $Sn^{2+}$?

In acidic medium,$K_2Cr_2O_7$ shows oxidising action as represented in the half reaction:
$Cr_2O_7^{2-} + XH^+ + Ye^- \rightarrow 2A + ZH_2O$
$X, Y, Z$ and $A$ are respectively:

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Ag + PCl_5 \xrightarrow{\Delta} AgCl + PCl_3$

$2 MnO_4^{-} + bI^{-} + cH_2O \rightarrow xI_2 + yMnO_2 + zOH^{-}$
If the above equation is balanced with integer coefficients,the value of $z$ is . . . . . .