When acidified $K_2Cr_2O_7$ solution is added to $Sn^{2+}$ salt,then $Sn^{2+}$ changes to . . . . . . .

Why does the following reaction occur?
$XeO_6^{4-}{(aq)} + 2F^{-}{(aq)} + 6H^{+}{(aq)} \rightarrow XeO_{3_{(g)}} + F_{2_{(g)}} + 3H_2O_{(l)}$
What conclusion about the compound $Na_4XeO_6$ (of which $XeO_6^{4-}$ is a part) can be drawn from the reaction?

In the reaction $Cr_2O_7^{2-} + X \xrightarrow{H^+} Cr^{3+} + H_2O + \text{Oxidized product of } X$,which of the following cannot be $X$?

$Zn$ reacts with $H_2SO_4$ and $HCl$ to produce hydrogen gas,but it does not produce hydrogen gas with $HNO_3$ because:

In the preparation of chlorine from $HCl,$ $MnO_2$ acts as

Which of the following species acts as the weakest reducing agent?