When an acidic solution of $K_2Cr_2O_7$ is added to $Na_2SO_3$,it turns green. Which of the following compounds is formed in this reaction?

$KI$ is oxidised into $I_2$ by using the reagent

Whenever a reaction between an oxidising agent and a reducing agent is carried out,a compound of lower oxidation state is formed if the reducing agent is in excess and a compound of higher oxidation state is formed if the oxidising agent is in excess. Justify this statement giving three illustrations.

Which of the following are redox changes?
$(i)$ Hydrolysis of $XeF_2$
$(ii)$ Thermal decomposition of $Ag_2CO_3$
$(iii)$ Reaction of $Al$ with $NaOH$
$(iv)$ Hydrolysis of $PCl_5$
$(v)$ Reaction of $NaCl$ with conc. $H_2SO_4$
Correct options are:

Which gases are formed by the oxidation of carbon with concentrated $H_2SO_4$?

Which of the following options are correct for the reaction
$2[Au(CN)_2]_{(aq)}^{-} + Zn_{(s)} \rightarrow 2Au_{(s)} + [Zn(CN)_4]_{(aq)}^{2-}$
$A.$ Redox reaction
$B.$ Displacement reaction
$C.$ Decomposition reaction
$D.$ Combination reaction
Choose the correct answer from the options given below: