What is the chemical name of the covalent compound p4o9?

P4O9 is an oxide of phosphorous

so it will named accordingly

There are four phosphorous atoms and nine oxygen atoms

four will be represented as "tetra"

Nine will represented as "non"

so the name of the compound will be

tetraphosphorous nonoxide

they it depends on if one believes about radioactivity, they make a geiger counter beep but maybe it was going to beep anyway electronics do wierd things all the time or it was programmed to beep near certain metals.

it’s previous models   because when i picked that son of a gun’s answer it was wrong look for previous models because they might make it a different letter