I wont say that R.D. sharma would be enough for IITJEE preparation.But yes you can always use RD sharma for buliding up basic concepts .But it wil be definitely better if you could use books like M.l. khanna and sl loney for iitjee preparation because rd sharma covers only boards syllabus and lacks problems upto the level of IITJEE .
ALL THE BEst
Ask IITIANs Expert