which are the most scoring topics in IIT JEE?

As we all very well know that IIT-JEE focusses on conceptual approach

For Physics mechanics,current eletricity,electromagnetism, electrostatics &SHM connected with rotational motion.

For Chemistry physical chemistry conceptual numericals which usually asks a thing  prior to whose calculation we  need to calculate another thing to get to final answer. Whereas organic is concerned to solve we should have command over mechanism,effects& relative dominance of effects we also need to be patient to consider options carefully

For Mathematics you need to have command on each and every concept of 11th &12th You need to have accuracy spped for which we need to practice very much

best of luck for exam