Need help naming compounds!!! Are my answers right

Write the chemical formula for the following compounds.
1) potassium carbonate------------------KCO3
2) dinitrogen tetroxide---------------------N2O5
3) magnesium hydroxide-----------------MgOH
4) iron(III) oxide-------------------------------Fe3O
5) tin(IV) oxide--------------------------------Sn4…
6) potassium chlorate---------------------KCLO3
7) carbonate tetrachloride---------------CO3Cl5
8) potassium permanganate------------KMnO4
9) ammonium dichromate----------------NH4(CrO4)2
10) potassium hydrogen phosphate--KHPO4



are those correct?
if not which ones are wrong?
(numbers are supposed to be the small number after the element showing how many were involved)

1.) K2CO3 The carbonate will have a -2 charge, and potassium is +1

2.)N2O4 Tetra is 4, penta is 5. Think of the PENTAgon, 5 sides

3.) Mg(OH)2 Magnesium is +2, while hydroxide is -1 charge

4.) Fe2O3 Oxygen (combines with metal to make oxide) has a -2 charge and iron (III) has a +3 charge. therefore, the charges seem to cross and they switch with each other when combined

5.)Sn2O4 ^^^ same as above, only with -4 charge for tin

6.) Correct

7.)CO3Cl4 Tetra is 4, memorization for that one

8.)K2MnO4 Permangante has a -2 charge, potassium has +1

9.) (NH4)2Cr2O7 Ammonium is +1 and dicromate is -2. dichromate is also written as Cr2O7 with a -2 charge

10.)K2HPO4 hydrogen phosphate has a -2 charge; potassium is +1

does all of this make sense?

1) K2CO3
2) No, tetroxide is 4 Oxygen. Pentoxide would be 5
3) Mg has a charge of 2+ and OH is 1- so it should be Mg(OH)2
4) Iron (III) has a 3+ and O is 2- so it should be Fe2O3
5) SnO2
6) Yes
7) Tetra is 4 once again.
8) Yes
9) (NH4)2 Cr2O7 (NH4 + and Cr2O7 2-)
10) K2HPO4 (PO4 is a 3- and the H+ creates a 2-)

Overall, make sure your charges balance. Be careful of compounds and adding charges. Remember that O is always a 2- and H is always a 1+. The parenthesis around transitional elements indicates their charge: Fe (II) is a 2+ while Fe (III) is a 3+

potassium carbonate is K2CO3
dinitrogen tetroxide is N2O4
magnesium hydroxide is MgOH2
iron(III) oxide Fe2O3
tin(IV) oxide is SnO2 (I think)
potassium chlorate is KClO3
carbonate tetrachloride is CCI4
potassium permanganate is right
ammonium dichromate (NH4)2Cr2O7
potassium hydrogen phosphate is K2HPO4