The oxidation number of Cr in CrO3 is +6
the x18bravo the x19s2 the x22fighter and the rs25
O.S. of Cr = +4
+6 for Cr, -2 for each O in Cr2O72-
Chromium is a metal. Atomic number of it is 24.
From another web site: Dr = Debit Record Cr = Credit Record