See it all depends on your efforts that is what it is. But as per the previous records of placement ratios and packages I am providing descending rank list of the branches that you have asked,

IIT Kharagpur Agriculture and food processing

IIT BHU metallurgy

NIT Trichy ECE

IIT Roorkee Polymer Science

Dear Applicant,

I hope you are doing well. So let's start with your queue. Each course in amazing in it's own way, so dont feel pressured at all. I would like you to think about which course you think will suit you well. Whether is it food technology or polymer science or agriculture choose the one that you feel you are capable to do.

Here is a little about polymer science and engineering, this course will be all about understanding of the chemistry, properties, processing, characterisation and application of polymers. It you like it go for it.

Than agriculture and food processing,

Here you shall learn methods and techniques are used to transform raw ingredients into food for safe consumption by humans or animals.

All the colleges you mentioned are good with their respective fields at the end it's up to you what is feel is good and what you actually wish to study.

Hope this helps