I bought POPO props because I wasn't watched what I'm buying -.-' can I mount POPO props on my "classic" motor nuts?? or there is some problem with size?

BTW this is propelers which I ordered:
https://www.banggood.com/HQProp-DP5_1X4_...rehouse=CN

and motors:
https://www.banggood.com/IFlight-XING-E-...rehouse=CN

Yes, you can still use POPO props on standard motors. The hole in the middle is 5mm, which is the standard prop shaft size on all motors capable of taking 5" props.