Mac mini with Core 2 Duo will be good for Xcode? If I have a Mac mini mid 2010 with 4 gb ram and Intel core 2 duo, will it be enough to run Xcode with safari or chrome?
Simple answer: Mac mini mid 2010 with 4GB RAM and Intel C2D can open Xcode and Safari/Chrome side by side. 

Ram replacement process can be found on iFixIt. if you decide more memory is needed for your workflow.