For B.Tech,
The classes go from 8 to 5. But it is rarely the case (almost never) where you have classes straight for 9 hours. Usually it’s either the first half or the second half in which you need to attend theory classes. The other half of same day is allocated for Labs. You can expect 4–5 theory slots and 2 Lab slots upto thrice in a week. Remaining 2 days in the week, you’ll have the 4–5 theory classes only.
PS. All of this very much depend on the subjects selected and the semester and whatever is written above is a general scenario for a student.