Which of the following is not true for $(i)$ $Zn +$ dilute $HCl$ and $(ii)$ $Zn +$ concentrated $HCl$?

In which of the following reactions, chlorine acts as an oxidising agent?
$(i)$ $CH_3CH_2OH + Cl_2 \longrightarrow CH_3CHO + HCl$
(ii) $CH_3CHO + Cl_2 \longrightarrow CCl_3CHO + HCl$
(iii) $CH_4 + Cl_2 \stackrel{hv}{\longrightarrow} CH_3Cl + HCl$
The correct answer is

In which of the following reactions is there no change in the valency (oxidation state) of the elements?

By passing $H_2S$ gas in acidified $KMnO_4$ solution,we get

Which of the following is oxidised by $SO_2$?

Which of the following oxidation reactions are carried out by both $K_2Cr_2O_7$ and $KMnO_4$ in acidic medium?
$A. I^{-} \rightarrow I_2$
$B. S^{2-} \rightarrow S$
$C. Fe^{2+} \rightarrow Fe^{3+}$
$D. I^{-} \rightarrow IO_3^-$
$E. S_2O_3^{2-} \rightarrow SO_4^{2-}$
Choose the correct answer from the options given below: