What is the name is the ionic compound cao
1 calcium oxygen
2 calcium oxide
3 calcium (i) oxide
4 calcium (ii) oxide

Almost without exceptions, the alkali metals (Li, K, Na,...) are in oxidation state (I) and the alkaline earth metals (Be, Mg, Ca, ...) are in oxidation state (II).

So without confusion, the naming of the metal part is simply the metal name, such as calcium oxide.

The Stock system (which indicates the oxidation state) is required only when the metal exhibits multiple oxidation states, such as iron (II) oxide or iron (III) oxide.  

Then again, older nomenclature applies the ending -ous to the lower oxidation state, and -ic to the higher.  Using the Latin name ferrum for iron, the previous compounds were named ferrous oxide and ferric oxide respectively.

I’d have to say no because without oxygen in the water the fish would all be dead. so if you want to fish for dead fish, pick the ponds with the lowest oxygen concentrations.

Only one reactant yields 2 or more products. meaning you will only have 1 product and it will break down into 2 or more products. eg. h2o -> h2 + o2