NCERT books are of very little importance.
Physics: HC Verma, Young & Freedman(used at MIT, USA), “Problems in Physics” by Abhay Kumar Singh
Inorganic Chemistry: JD Lee, OP Tandon
“Physical Chemistry” by Robert A. Alberty, Robert J. Silbey (both from MIT, USA)
Organic Chemistry: Morrison & Boyd, Paula Yurkanis Bruice
“Calculus:graphical,numerical,algebraic” by Thomas,Finney, Demana, Waits (one or more authors from MIT, USA)
Arihant Integral Calculus, Arihant Differential Calculus, Arihant “Vectors and 3-D geometry”
Trigonometry: SL Loney
Coordinate geometry: SL Loney
Algebra: “Challenge and Thrill of Pre-College Mathematics” by V. Krishnamurthy
						

							
Yes NCERT prepares a very strong base for iit aspirants
If a student has all his NCERT concepts clear then he can score 40% of marks in iit exam
And the cutoff remains around 45-50% 
So with NCERT book and a little other practice you can be easily selected in iit
BEST OF LUCK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!