Hello  Isha

you can read this article by visiting our website

https://engineering.careers360.com/articles/crack-gate-why-practice-of-previous-years-papers-must

thank you and GOOD LUCK!!!

Hi

Their is no particular answer for that. It depends on the person who sets the paper. 

But if you for to see,  all the previous year paper are based on similar concept. 

Some time even Same question is repeated with minor changes.  The question are asked on similar concepts. 

60% of the concept remains same only the framing of question may vary