Question

помогите, скажите плиз что такое PO3

Answer 1

Если РО3{-}, то это метафосфат-анион.
Если просто РО3, то это что-то несуществующее.

Answer 2

PO3 is not a well-known acronym or abbreviation that can be easily identified. It is possible that PO3 may refer to different things depending on the context. However, without further information or clarification, it is difficult to provide a specific answer.

If you can provide more details or context about what PO3 refers to, I would be happy to assist you further.