Mono and di are Greek numbers, mono means one, mostly u will find it for the thing which is like ONE, (Idk) Like, in maths you use Monomials,, which meAns one term, so like that.... and DI means two , mostly you will find it for two things,,, like in Science, DIoxide,,, so you need to oxides to make dioxide,, CARBON-DIOXIDE,,,
HOPE THIS HELPS!