$Na_2S_2O_3$ reacts with moist $Cl_2$ to form $Na_2SO_4$, $HCl$, and $X$. Which one of the following is $X$?

The product of $I^-$ with $MnO_4^-$ in acidic medium is

Permanganate $(VII)$ ion,$MnO_4^-$,in basic solution oxidises iodide ion,$I^-$,to produce molecular iodine $(I_2)$ and manganese $(IV)$ oxide $(MnO_2)$. Write a balanced ionic equation to represent this redox reaction.

For the redox reaction $MnO_4^- + C_2O_4^{2-} + H^{+} \to Mn^{2+} + CO_2 + H_2O$,the correct coefficients of the reactants for the balanced reaction are:
$MnO_4^-$ : $C_2O_4^{2-}$ : $H^{+}$

How many moles of hydrazine $(N_{2}H_{4})$ can be oxidized into $N_{2}$ using $\frac{2}{3}$ mole of bromate ions $(BrO_{3}^{-} \to Br^{-})$ :-

In the reaction $Zn + 2H^{+} + 2Cl^{-} \to Zn^{2+} + 2Cl^{-} + H_2$,the spectator ion is