Hello,
Indian Maritime University conducts IMU CET for admission into various courses offered by the institution.
Exam is of 3 hours duration, having 120 questions in sections : English, GS, Physics, Chemistry, Maths, General Aptitude.
The questions are of conceptual nature and require a thorough revision of upto class XII topics.
So NCERT would be the best books to go with.
For GS and Aptitude you can refer to online sources.

Follow this link for more information
https://www.google.com/amp/s/engineering.careers360.com/articles/imu-cet/amp

Good luck