my score is 73% in the karnataka state board exam so will I come under top 20 percentile
I would suggest you to check previous year top 20 percentile for NITs & IITs -
https://josaa.nic.in/webinfocms/Handler/FileHandler.ashx?i=File&ii=86&iii=Y
https://josaa.nic.in/webinfocms/Handler/FileHandler.ashx?i=File&ii=87&iii=Y
Good Luck!!!