MgC2O4 is most probably named 'magnesium oxalate', though isomers might exist.
The symbol for magnesium in the periodic table is Mg .
The chemical formula of Magnesium IV oxide is: MgO. ****************2nd Opinion ****************** Magnesium doesn't form +4 ions, so I'm thinking the original question was probably about manganese(IV) oxide, which would be MnO2.
No, magnesium oxide is practically insoluble in water; the solubility at room temperature is 0,086 g/L.