This is one of the most important part of BCS preliminary Syllabus, specially for science students. 15 marks allotted for Mental ability. You need to answer six different topics- 1. Verbal Resoning 2. Problem Solving 3. Spelling And Language 4. Mechanical Resoning 5. Space Relation 6.Numerical Ability
I had experience of solving zigzag and Mogoj Dholai problems(two magazines published by two prominent BENgali Newspapers). Such habit can help you a lot.