I will be appearing foriit jee in 2018. Which lessons should I study this year in 11th and which books should I prefer?

@ RADHIKA 
all the chapters which are there in ncert are vital for jee prep. 
so, make a coverage of all the chapter that are in the ncert syllabus , and if u will be in cbse syllabus , then it will not problem you , 
u can check the syllabus in the jee main website as well as the askiitian website also . 
below are some topics i am listing which are of extreme importance of jee , that required special attention 
PHYSICS 
1- LAWS OF MOTION 
2- ROTATIONAL MOTION 
3- MECHANICAL PROP. OF FLUIDS 
4- OSCILLATIONS 
5- THERMODYNAIMCS 
CHEMISTRY 

1- CHEMICAL BONDING 
2- HYDROCARBON 

3- ORGANIC NOMENCLATURE AND REACTION INETRMEDIATE 
4- THERMODYNAMICS 
5- EQUILIBRIUM 
MATHS 
1- CONIC SECTIONS 
2- TRIGNOMETRY 
3- PERMUTATION AND COMBINATION , PROBABILITY 
BOOKS THAT U HAVE TO REFER 
1- CONCEPT OF PHY BY H C VERMA 
2- MATHS BY M L KHANNA / A DAS GUPTA (ANY ONE ) 

3- ORGANIC CHEMISTRY BY MORRISION AND BOYD 
4- INORGANIC CHEMISTRY BY J D LEE 
5- PHYSICAL CHEMI BY P BAHADUR 
u can also take askiitian self study pack and test series , they aree actually awesome . 

HOPE IT HELPS 
ALL THE BEST ..

please visit the below mentioned link to check syllabus

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thanks again