Hi Megha, By clicking given link you can see or download UPSEE 2018 paper 1 code-AD -

https://files.aglasem.com/view/engg3.php?link=//drive.google.com/file/d/1A4yrbbVttlupQVwWUlcdf1yjrAyBnc2q/preview&title=UPTU+2018+Answer+Key+Paper+1+Set+AD

if you want others papers with answer keys then check it out given link:
https://engineering.careers360.com/articles/upsee-answer-key

good luck