It is the formula of Dichromate ion
"2 plus 2" is not a scientific formula. In fact, it is not a formula of any sort.
What is the molecular formula of 2-Butyne
The formula: Zn(ClO)2 is for Zinc Hypochlorite.
Formula: CrO4-2
The chemical formula of carbonate anion is (CO3)2-.The chemical formula of magnesium cation is Mg2+.
The chemical formula for beryllium hydroxide is Be(OH)2.
The formula for calcium chlorite is Ca(ClO2)2.
The chemical formula for tin(II) hydroxide is Sn(OH)2.
Formula: Hg2(NO3)2
The barium chlorate formula is Ba(ClO3)2.
Hg3PO4 is the chemical formula for mercurous phosphate.
Formula: C2O4-2