My brother is a B.Tech pass out from Electronics Engg. at IIT (BHU). His experience was absolutely disappointing and he told me about the bitter reality of IIT BHU. The faculty is very unqualified and the curriculum is obsolete and irrelevant to the current trends in the industry.
You will be surprised to know that some profs don't even have Ph.D. despite the fact that they are the only professors for that subject in the dept. Also, the administration of the college will provide a total of friction against any kind of endeavors you may seek. You will find some professors really difficult to tolerate. Though the current HOD is an excellent professor/researcher and very progressive/dynamic; so is not the case with the entire dept.
The TPO cell is very stagnant; they have a very weird logic of inviting core companies. Getting a new company approved for placement is next to impossible. The placement rate itself is very very bad. As per the research quality of the department, there are no research groups for many important core domains. It's extremely disappointing with it being an IIT and all and having worse research scope than an NIT in many fields. Also, they won't encourage independent research.
You don't have enough electives to choose from. The classrooms are gloomy.
While you can, go to a good NIT, or a BITS Pilani college. Electronics Engg in IIT (BHU) is a bitter disappointment.
If you are looking for a selection to the college, it will highly depend on if you have been called for an interview.
Now when it comes to institutes like IOCL, BPCL, NITIE, and many other PSUs, if you have an AIR of 1000 for mechanical engineering, your chances of bagging an interview will entirely boil down to the reservation system.
Lastly, if you are called for an interview, you are going to face a panel of experts who may or may not stick to your subject of preference. So, you should definitely brush up on all your syllabus. This includes general aptitude and mathematics.