That compound is beryllium oxalate. Beryllium, an alkaline earth metal, has two valence electrons, which it will lose to the oxalate polyatomic ion.
BeC2O4 = 97.0 g/1 mol BeC2O4-3H2O = 151.0 g/1 mol 3.21 g BeC2O4-3H2O * 1 mol/151.0 g = 0.021258 mol BeC2O4-3H2O 0.021258 mol BeC2O4-3H2O * 97.0 g/1 mol = 2.06 g BeC2O4
(2C x 12.011)/(Be x 9.012 + 2C x 12.011 + 4O x 16 +6H x 1 + 3O x 16) (24.022g C/ 151.034g) x 100% = 15.9%