What is the correct name for the ionic compound Ca2P5

It is calcium phosphide.

Explanation:

Calcium phosphide is a salt like material that is composed of calcium and phosphorus in the ratio of 2:5. It has the appearance of red brown Crystalline salt.

It is use as rodenticide to kill rats.

It is also use in fire works.

Calcium phosphorous

Explanation:

First, this compound is a mixture of the following elements:

Ca: Calcium

P: Phosphor

Now, both of these elements are united as a binary compound, the metal and a non metal. When we have a binary compound with a metal and non metal, (When the non metal is not hydrogen or oxygen) this usually becomes a salt. A bynary salt. So a binary salt, we should name like this

In this, we should name first the metal and then the non metal with the sufije ous. In this case:

Calcium phosphorous.

Then the name of this salt is that.