What will happen when copper sulphate solution is stored in aluminium vessels?

Number of moles of $K_2Cr_2O_7$ reduced by one mole of $Sn^{2+}$ ions is

Oxidation of thiosulphate $S_2O_3^{2-}$ ion by iodine gives

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$2NaI + MnO_2 + 2H_2SO_4 \to MnSO_4 + Na_2SO_4 + I_2 + 2H_2O$

In an experiment,$50 \ mL$ of $0.1 \ M$ solution of a metal salt reacted with $25 \ mL$ of $0.1 \ M$ solution of sodium sulphite. The half-equation for the oxidation of sulphite ion is $SO_3^{2-}{(aq)} + H_2O_{(l)} \to SO_4^{2-}{(aq)} + 2H^{+}{(aq)} + 2e^-$. If the oxidation number of the metal in the salt was $3$,what would be the new oxidation number of the metal?

What is the equivalent weight of $IO_4^-$ when it is converted to $I_2$ in an acidic medium?