Colleges in Lucknow

50% is not needed. Any educational institute just need minimum 45% aggregate marks in 12th to take students.
So, don't worry, if you're above 45%, clear the entrance exam and go for it.

For answering your question, I am attaching a link below:
https://www.shiksha.com/university/bbau-babasaheb-bhimrao-ambedkar-university-lucknow-26165/admission

No, you should have scored at least 98 percentile for getting admission in Jamia.

Top M.Sc colleges in Lucknow are as follows:-
1) Babasaheb Bhimrao Ambedkar University
2) Dhanvantri Institute of Professional Education
3) Lucknow Christian College etc.

Eligibility Criteria for Admission:
Minimum 45% required in class 12th with Mandatory Subjects: Mathematics, Physics. Candidate must have studied any one of Chemistry, Biotechnology, Computer Science, and Biology as optional subject. Admission is through counseling based on the rank obtained in Uttar Pradesh State Entrance Examination (UPSEE). https://www.shiksha.com/b-tech/course/b-tech-in-computer-science-and-engineering-institute-of-engineering-and-technology-iet-lucknow-86916

Hi,
Admission Process:
The admission based on Written and Interview.
Eligibility Criteria:
The candidate should have passed50% marks either in the Bachelor Degree and/or in the Master's degree in Science/ Social Sciences/ Humanities. Bachelors in Engineering or Technology with specialization in Science and Mathematics with 55% marks.
For more details information you can see below link:
https://www.shiksha.com/teaching-education/course/b-ed-special-education-hearing-impairment-dr-shakuntala-misra-national-rehabilitation-university-lucknow-181225

IIM-Lucknow cut-off is around 97 percentile and if you are an OBC category student then you can get a call at 94 percentile also.
Now, what are your chances? It depends on your preparation for CAT. If you are preparing daily and in the right way then you have 100% chance as you have 7 or more months before the exam which is plenty. Prepare properly for GD/PI and get into one of the IIMs.

Yes, you can now join the Wisdom School of Management. No matter as in which year you've passed class 12th. You can now apply for it and based on the performance in the respective entrance exam you'll get a seat or you can take admission through management quota.