One litre of $0.15 \ M$ $Na_2SO_3$ aqueous solution is mixed with $500 \ mL$ of $0.2 \ M$ $K_2Cr_2O_7$ aqueous solution in acid medium. What is the number of moles of $K_2Cr_2O_7$ remaining in the solution after the reaction?

Match the following types of reactions in List-$I$ with their corresponding unbalanced equations in List-$II$.

List-$I$ (Type of reaction)	List-$II$ (Unbalanced equation)
$A$. Combination reaction	$(i)$ $AgNO_3 + CaCl_2 \longrightarrow AgCl + Ca(NO_3)_2$
$B$. Decomposition reaction	$(ii)$ $Cl_2 \longrightarrow Cl^- + ClO_3^-$
$C$. Disproportionation reaction	$(iii)$ $Mg + N_2 \longrightarrow Mg_3N_2$
$D$. Displacement reaction	$(iv)$ $KClO_3 \xrightarrow{\Delta} KCl + O_2$

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

Which of the following is not correct?

In basic medium,$CrO_{4}^{2-}$ oxidises $S_{2}O_{3}^{2-}$ to form $SO_{4}^{2-}$ and itself changes into $Cr(OH)_{4}^{-}$. The volume of $0.154 \ M \ CrO_{4}^{2-}$ required to react with $40 \ mL$ of $0.25 \ M \ S_{2}O_{3}^{2-}$ is ........... $mL$ (Rounded-off to the nearest integer).

In chloro-alkali industries,during the Solvay ammonia process,a redox change occurs during: