Which compound can change the colour of an acidified potassium dichromate(VI) solution from orange to green?
Na3PO4\text{Na}_3\text{PO}_4Na3PO4
NaClO4\text{NaClO}_4NaClO4
NaNO2\text{NaNO}_2NaNO2
MgSO4\text{MgSO}_4MgSO4