Does 11th and 12th portion of PCM is helpful in B.Tech.?If yes then how much is it important for every branch?

dear rahul 
yes , 11^th and 12^th pcm are very very imp and they are oncept building foundation for btech . 
without that you will not understand anything in btech frst year , 
for example u took mechanical engg , then you need to know about laws of motion , inertia , and all about rigid body dynamics and mechanics . 
and also if u opt for chemical engg , then u will req the reaction of chemical their . 
and if mining engg , then mettalurgy chap of class 12^th will be very helpfull their . 

REGARDS 
KINDLY APPROVE