It's an oxonium ion, but specifically it's the hydronium ion. Oxonium means any positively charged ion where an oxygen atom has three bonds (a double bond and a single bond count as three bonds).
+1
sp2
-2 for O +1 for each H
Ru has oxidation number +8, O has oxidation number of -2
The overall oxidation number is -2 so the average oxidation number of O is -1.
Oxidation number of chlorine is +7. oxidation number of O is -2.
The oxidation number for H is +1, and the oxidation number for O is -1.
The oxidation numbers for the atoms in magnesium oxide are: Mg+2 and O-2.
-2 for O +1 for each H
Each of the hydrogen atoms in H2 has an oxidation number of 0.
Ru has oxidation number +8, O has oxidation number of -2
The overall oxidation number is -2 so the average oxidation number of O is -1.
Oxidation number of chlorine is +7. oxidation number of O is -2.
The oxidation number for H is +1, and the oxidation number for O is -1.
Oxidation number of Si is +4.Oxidation number of O is -2.
+6, because the oxidation number of oxygen is -2x3=-6
Oxidation number of Nb is +4. Oxidation number of O is -2.
Oxidation number of N is +1. Oxidation number of O is -2.
Oxidation number of C is +3. Oxidation number of O is -2.