Legal Reasoning and Legal Knowledge collectively forms Legal Aptitude. So you can expect two types of question. First type of questions that are based on legal knowledge are from basics of Tort Law, criminal law, etc. to legal maxims and Constitution. Other than this some important landmark cases, certain Acts, judiciary, jurisdictions, etc.
In second type of questions that is legal reasoning candidates will be presented with a legal principle and asked to apply that to a given set of facts. So this part is trickier as you have to act as a judge and give decision on the basis of provided principle and facts. Here you have to limit yourself with the given facts only and need to ignore any thing over and above it.
Students preparing for Clat and other legal entrance exam should study basics of following laws as it will help them in comprehending various legal term and understanding the given situation
The Indian Contract Act, 1872
Indian Penal Code
Constitution of India
LEGAL APTITUDE Chapters