sir i am preparing for iit(2015) in kota and i have most of the concepts clear but due to some reasons i spoiled some parts of my 11th and beacuse of that i got depressed i dont know what to do now please suggest me some tips what to do ??how many hours do i study and etc ?? plz

You have to work hard. Brush up all your 11th concepts with ncert chemitry and maths. Refer arihant d.c.pandey for physics. Solve numericals from coaching package and h.c.verma. You dont need 15 hours of study. Just study 8-9 hours everyday. That 8-9 hours should be of quality. Dont deviate from the topic in this time. Take small 15 minutes brakes after every 1 hour of study. Good luck!!!! Please approve my answer by clicking approved if you liked it.