Lucknow

Yes, it is not tough to get in there. Apply for it and all the best.

If you want to go only for government college for BCA in Lucknow then you should opt :
- University Lucknow
- BundelKhand University
admission is based on the merit obtained by the candidate in the entrance test conducted by the universities.

No chance, but keep an eye on the counselling process and think about some other options as well.

It will depend on the counselling pattern and zonal distribution of qualified candidates whose ranks are above than yours. So give first preference to IHM Chandigarh and then others. Do not select Delhi as you will not get it at this rank; it is very low for IHM Delhi.

With an OBC rank of 2435 your general rank would be in between 10k-12k (a simple guess), I'm sorry to say with this rank getting into IET is next to impossible so don't hold any false hopes you can get into JSS and here also getting CS and IT would be tough for you.
Getting any other govt college is also difficult and even if you get one you might end up in not so favourable branch.
At last, what I would suggest is that if you have a one more chance in JEE MAINS then go for it because believe me giving another year to study is worth regretting about the college you would be with this rank to make myself clear try avoiding AKTU.

Go for CS or ECE Jaypee Noida if you want better infrastructure exposure and if money is not a constraint. Consult the seniors of Jaypee regarding placements. I can only tell you that IET Lucknow will definitely provide you ample opportunities as far as placement is concerned.

First of all, you can't expect placement in New IIITs. New IIITs will not give you good industry exposure. It will take at least 10-15 years to get established. Better to go for old GFTI colleges rather than going in New IIITs.

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Yes, there are good chances for you to get admission in both the colleges.

Yes, you can but it depends on the college which is offering that option.