In order to get admission in postgraduate programs with MHRD & some other government scholarship & assistantships in engineering colleges & institutions, you have to clear GATE i.e Graduate Aptitude Test in Engineering. For this the foremost important eligibility is that you must have the bachelor’s degree in Engineering i.e B.E. or B.Tech.

GATE Exam : There are various subjects for GATE Exam. You just have to choose one in which you want to do the Post graduation. The subject are -
Computer Science CS
Information Technology  IT
Electronics & Communication ECE
Electronics & Electricals EE
Instrumentation Engineering IN
Mechanical Engineering ME

GATE Instrumentation question papers : In order to get an idea about the pattern of questions asked in the exam, you must have the question papers of the previous years. For this, I tried to provide you with the links to download the papers.
GATE Instrumentation Question Paper 2010 : Download
GATE Instrumentation Question Paper 1999 : Download