When silver nitrate is heated to red hot,what is formed?

In which of the following reactions is there no change in valency?

$H_2O_2$ reduces $KMnO_4$ in acidic medium to '$x$' and in basic medium to '$y$'. What are $x$ and $y$?

Match the chemical reactions given in List-$I$ with their types given in List-$II$:

List-$I$	List-$II$
$A$. $TiCl_{4(l)} + 2Mg_{(s)} \xrightarrow{\Delta} Ti_{(s)} + 2MgCl_{2(s)}$	$I$. Disproportionation reaction
$B$. $2H_2O_{2(aq)} \rightarrow 2H_2O_{(l)} + O_{2(g)}$	$II$. Metal displacement reaction
$C$. $C_{(s)} + O_{2(g)} \xrightarrow{\Delta} CO_{2(g)}$	$III$. Decomposition reaction
$D$. $2NaH_{(s)} \xrightarrow{\Delta} 2Na_{(s)} + H_{2(g)}$	$IV$. Combination reaction

How many electrons $(e^-)$ are gained by the oxidizing agent $KMnO_4$ to convert into $MnO_4^{2-}$,$MnO_2$,$Mn_2O_3$,and $Mn^{2+}$ respectively?

Calculate the millimoles of $SeO_3^{2-}$ in solution on the basis of following data: $70 \ mL$ of $\frac{M}{60}$ solution of $KBrO_3$ was added to $SeO_3^{2-}$ solution. The bromine evolved was removed by boiling and excess of $KBrO_3$ was back titrated with $12.5 \ mL$ of $\frac{M}{25}$ solution of $NaAsO_2$. The reactions are given below.
$I. \ SeO_3^{2-} + BrO_3^{-} + H^{+} \to SeO_4^{2-} + Br_2 + H_2O$
$II. \ BrO_3^{-} + AsO_2^{-} + H_2O \to Br^{-} + AsO_4^{3-} + H^{+}$