Thapar University

Hi Shivangi, I totally agree with Puneet, either your brother can wait for second counselling and if he still doesn't get Mechanical then he can take admission in the first year.
I am suggesting this to you because first year's syllabus is mostly same and he can still change his stream before 3rd semester starts by giving a TU-Test which most student who wish to change their streams, also the Syllabus is same as IIT syllabus so it won't be any difficult for him.

Just pay fee and if you are not interested in electronics don't select it and automatically your name will remain in other rounds.

Yes, you can get admission in Thapar University for BE in Computer Engineering?

You should wait for other cut-off lists.

You can book your seat online. And at counselling time you have to get all the relevant documents for verification process.

It's more or less the same, name does not matter, subjects do.
Thapar has one of the best curriculum structures so no need to worry. Go for it.

It will be difficult for you to get admission in IIIT-Allahabad if you are outside state student, but for Thapar University thumbs up.

Yes, you can get admission in the college, but you will not be able to get streams like COE and ENC.