hey charith

In CSE , if you work a little hard it is easy cause the marks are divided into assignments , quizzes and projects which are pretty basic, if you complete them and submit on time , then you can easily get a C grade , if you want to get A's or B's work for 2 hours a day and you will get it .

In Mechanical , it is the same , except you have more VIVAs and Lab , you have to work harder for 8 CGPA cause there arent many assignments given .

In ECE, you have to work for a minimum of 3 hours a day because the portion is vast , you have very few assignments and very few quizzes , most of the weightage is given in your minor and major exams , every subject teacher will demand a project from you and it will get stressful to complete them. Nevertheless, if you are genuinely interested  you wont feel that its difficult, just keep studying up every now and then and you can do it !

Cheers