My AIR is 18312(gen.14414), will i get chemical branch in nit surat or surathkal ?

No in those NITs u can'r get the same stream.and in now days electronics and communication and computer science branch is doing so much well and exactly the main thing is the placement with high package salary are availed for only these two streams.and the top colleges where u are eligible for the s

Yes be sure. don worry you will