[locagata48]

Write formulas for the following substances

1) Sodium peroxide  Na2O2
2) Perbromic acid   HBrO3
3) Silicon dioxide  SiO2
4) Chromium (III) oxide  Cr2O3
5)Cobalt (III) nitrate  Co(NO3)3
6)Ammonium phosphate  (NH4)3PO4

[Yggdrasil]

All correct except for #2.  HBrO₃ is bromic acid.

[yukiheart]

1/ Na-O-O-Na
2/HO-Br(O2)
3/O=Si=O
4/ O=Cr-O-Cr=O
5+6/ I cant draw in this topic!!!

[macman104]

1/ Na-O-O-Na
2/HO-Br(O2)
3/O=Si=O
4/ O=Cr-O-Cr=O
5+6/ I cant draw in this topic!!!

It doesn't ask for the structures, just the formulas

[yukiheart]

I m sorry!!!
#2 is bromic acid and : in wikipedia write :
The compound perbromic acid, HBrO4, is an oxygen acid of bromine. Other names include hydroxy-γ7-bromanetrione and hydroxidotrioxidobromine. Perbromic acid is unstable and cannot be formed by displacement of chlorine from perchlorate, as periodates are prepared. The acid was discovered when a sample of radioactive selenate, SeO42−, was left to decay. It is a strong acid, and strongly oxidizing, and is the least stable of the halogen(VII) acids. It decomposes rapidly on standing to bromic acid and oxygen, with the evolution of brown bromine vapour.

[AWK]

I think this is a test for nomenclature. Then name of perbromic acid can be used.

It decomposes rapidly on standing to bromic acid and oxygen, with the evolution of brown bromine vapour.

I doubt about this statement from wikipedia