one mole is 6.02×10^23
an even number
assuming there is a whole number of moles in existence (odd or even) then yes, there are an even number of molecules in existence ( and will always be according to the law of preservation of mass). How ever, if there are whatever.3 moles in existence, then no, there is an odd number.
there is no way to be for sure, and if anyone tells you otherwise, tell them that theyre full of shit, because there is no way to be sure, and that with as many made up values in science ( such as the AMU, was based on hydrogen, now its based on carbon 12 i believe) that even if a definite figure was brought into light, there is no way its as accurate as they say it is