Test is common for all the departments. Hence, one might encounter questions not related to his/her branch. Almost all courses are covered in this test.
Prepare for topics relevant with current affairs. Get an idea of how exactly a group discussion takes place.
Be thorough with Fluid Mechanics. Questions related to pumps, efficiency of pump, NPSH, pressure drops in pipes are expected. Basic questions related to CRE and Heat transfer can be asked. You'll be asked in depth on the subject of your interest. Prepare for few HR ones as well.