Can anyone tell me which Surahs in Quran mention Doomsday & Dajjal?
You can find detailed knowledge in Ahadees. Apologies for not copying Ahadees here as I have them in book form but you should read Kitab-ul Fitn and Kitab-ul Ilm of Sahi Bukhari and Sahi Muslim (especially Kitab-ul Fitn).
Detailed Ahadees on Dajjal and Doomsday are available there.
In Holy Quran, knowledge on these is available in various Ayaats of various Surahs. You need Tafaseer to interpret and understand the context. I'll try to help you with a comprehensive list soon.
Regards,