Hii Pooja
Basically in aptitude test you won't find any particular syllabus so there will be more logic based questions that will be asked and after that there will be an interview round in which they will ask you general stuffs like your biodata,why you are interested in this etc so just keep calm and be confident.
All the best

thanks for query

There is no particular subject or book you need to read. There will be questions on 
- basic mathematics you learnt from 8th-12th grade (no calculus). 
- General IQ (there will be more questions from this section).
- Science (physics and chemistry. Very basic, again. Like: phenolphthalein turns pink in _____ medium).
- A bit of social science (history, especially).

Most questions are primary. The test is to check if you are strong with your fundamentals. The interview that follows is important. Good luck!