1. Mathematics - Higher Engineering mathematics by B. S. Grewal

2. Process Calculation - Chemical Process Principles Part-I by Hougen and Watson

3. Chemical Engineering Thermodynamics - I - Engineering thermodynamics by cengel and boles

4. Chemical Engineering Thermodynamics - II - Introduction to chemical engineering thermodynamics by smith

5. Fluid Mechanics and Heat Transfer - unit operations of chemical engineering by mccabe and smith

6. Mass Transfer - mass transfer operations by Treybal

7. Chemical Reaction Engineering - Chemical Reaction Engineering by levenspiel

8. Instrumentation and process control - Process System analysis and Control by coughanowr

9. Chemical Technology - Outlines of Chemical Technology by Dryden

10. Plant Economics and Design - Plant Design and Economics for Chemical Engineers by Timmerhaus

I hope these books will clear your concepts and help you in your preparation. All the best!