Hello Lakshmi,

Your rank in GATE is 736. IISC is the generally the first preference of the students who wish to pursue M.Tech and so mostly the rank holders from 1 to 100 fill up the seats.

There are other factors also like the number of seats, number of people who apply to this institution, level of the GATE paper, etc which should be considered but if you see the trends of the previous years you don't have a good chance at IISC.

You can try IIT BOMBAY or IIT DELHI which are also good institutions for M.Tech and at this score you may get admission there.

All the best.