If ur in cbse and grade 10 then do as i say
First go for the hard chapter if u atleast have a time of 10 days but if u have less time go for the lessons u know or the one which is easy for u and go through the lesson which u think is hard so that ur ready overally.But u should atleast read the book and notes given by ur teacher for the hard lesson and try byhearting each and every para and the notes in easy lessons so u have the chance gettin max marks in geography.
BEST OF LUCK FOR YOUR EXAMS:)