I have got 78 percentile in jee and i belong to obc category ...kindly tell can i get admission in autonomous or government colleges?? and am i qualified for jee adv???

Hello.
For your kind information I am informing you that the criteria of percentile is entirely different with the rank criteria in JEE mains from when NTA is organising this exam, so it is quite difficult to predict a college on the basis of your percentile still I am providing you a link below where you can predict college on the basis of your rank which you have in JEE mains exam, the link is given below:

and you didn't mentioned year in which you scored that percentile so I am providing you a link below where you can see cut off marks for JEE mains in all year till now , it is quite difficult to predict your actual rank so your approximate rank would be at at your mentioned percentile: 191,182.
Let suppose number of candidate in April exam increased to 12,00000 then you can calculate your rank by using the below formula:
((100- your percentile score) X 869010/100.
You can use your approximate rank to have a probable idea of your admission by checking if it  lie in the cutoff from the below link.
https://engineering.careers360.com/articles/jee-main-cutoff
Best of luck.