Gold (111) chloride
calcium carbonate
hydrobromic acid
what’s the formulas to these compounds

Explanation:

Gold (111) Chloride:

AuCl₃

The oxidation state of gold is +3.

Chlorine is present in group seventeen and have seven valance electrons . Thus it accept one electron to complete the octet and show oxidation state -1.

When it react with gold(III) three chlorine atoms are combine with one gold atom to make compound overall neutral.

Calcium Carbonate:

CaCO₃

Carbonate formula is CO₃²⁻ . It means it carry -2 charge . Calcium is present in group two. It has two valance electrons and lose them to get complete octet thus shows +2 oxidation state.

When it combine with carbonate the overall compound is neutral because -2 and +2 charges cancel each other.

Hydrobromic Acid

HBr

Hydrogen has one electron while bromine has seven valance electrons. Bromine require one more electron to complete the octet. It react with hydrogen by sharing of one electron of hydrogen and form polar covalent compound.