But this is not the right answer of my question.i am asking about IISc not for IISER admission Please give me information about iisc 

Hello there!
Greetings!

Sorry , I mistook iisc for iiser.

The Indian Institute of Sciences(IISC), Bangalore will offer admission for Bachelor of Science throughJEE Main, JEE Advanced and KVPY to the candidates.

Candidates must have passed their class 12thor equivalent in 2019

Candidates currently in their class 12thand are likely to pass in 2020 are also eligible to apply

Candidates must have studied Physics, Chemistry and Mathematics as compulsory subjects in the qualifying examination

Candidates who have studied Biology, Electronics, Statistics, Computer Science, etc. along with Physics, Chemistry and Mathematics are also eligible.

Candidates must have secured at least 60% marks or first grade or equivalent grade in their Class 12thor equivalent examination.

So there's no upper age limit,  once you qualify jee mains with good  score. You can get into iisc.

For more information go through :-
https://engineering.careers360.com/articles/iisc-bs-eligibility-criteria
Thankyou

Then after clearing jee mains or jee advanced i can take admission in iisc in 2020 , is there not matter that my date of birth is 9/1/1995.i will be 25 year old in 2020. But IIT colleges can not give admission at this age. Is it true?