The Union Public Service Commission (UPSC) conducts various civil service examinations in India. The recommended books for UPSC preparation, including the National Council of Educational Research and Training (NCERT) books, are as follows:

1. History:
   Class 6: Our Past - I
   Class 7: Our Past - II
   Class 8: Our Past - III, Part I
   Class 9: India and the Contemporary World - I
   Class 10: India and the Contemporary World - II
   Class 11: Themes in World History
   Class 12: Themes in Indian History - I, II, and III
   (Note: Kindly give just a overview to open your mind and understanding of history as a subject. After that directly jump to the standard books like SPECTRUM ,NITIN SINGHANIYA )

1. Geography:
   Class 6: The Earth Our Habitat
   Class 7: Our Environment
   Class 8: Resource and Development
   Class 9: Contemporary India - I
   Class 10: Contemporary India - II
   Class 11: Fundamentals of Physical Geography, Practical Work in Geography - I
   Class 12: Fundamentals of Human Geography, Practical Work in Geography - II, India - People and Economy
   (KINDLY give just a overview to the class 6,7,8,9,10,and after that make sure to give very depth reading to class 11 and 12 geography books. And after that if you think there is more to explore than go to GC Leong )

1. Polity (Political Science):
   Class 9: Democratic Politics - I
   Class 10: Democratic Politics - II
   Class 11: Political Theory
   Class 12: Contemporary World Politics, Politics in India Since Independence
   (Although i mention the book as you asked for the polity ncert. But you dont need to read all this books just go with the standard book M Laxmikanth. This alone boook is sufficient to cover entire syllabus of polity for upsc preparation)

1. Economics:
   Class 9: Economics
   Class 10: Understanding Economic Development
   Class 11: Indian Economic Development
   Class 12: Introductory Macroeconomics, Introductory Microeconomics
   (Just take an overview of that ncert books than supplement it with the some standard books like Ramesh singh)

1. Science:
   Class 6-10: Science (NCERT books of respective classes)
   (Although i mention the book as you asked for the science ncert. But you dont need to read all this books just go with the Lucent )

1. Environment and Ecology:
   Class 12: Biology: Last Four Chapters (12th Biology book, Unit X-XIII)
   (Although i mention the book as you asked for the Environment ncert . But you dont need to read all this books just go with the standard notes of Shankar IAS )

These NCERT books provide a strong foundation for understanding the basic concepts in each subject. However, it's important to note that for the UPSC examination, you'll need to supplement your preparation with additional reference books, newspapers, magazines, and other study materials to cover the entire syllabus comprehensively.

Apart from NCERT books, you can refer to these standard textbooks(as mentioned above), reference books, and study materials specific to each subject as recommended by experts and previous successful candidates. Additionally, referring to current affairs magazines and newspapers will help you stay updated on the latest events and developments, which is crucial for the UPSC examination.
ALL THE BEST !!!!