Civil Servant (IAS/PCS) exams

UPSC Prelims Syllabus for GS Paper (Prelims Paper I)
Current events of national and international importance. History of India and Indian National Movement. Indian and World Geography Physical, Social, Economic Geography of India and the World. Indian Polity and Governance Constitution, Political System, Panchayati Raj, Public Policy, Rights Issues, etc. Economic and Social Development Sustainable Development, Poverty, Inclusion, Demographics, Social Sector initiatives, etc. General issues on Environmental Ecology, Biodiversity and Climate Change that do not require subject specialization General Science
Syllabus for CSAT Paper (Prelims Paper II)
Comprehension
Interpersonal skills including communication skills
Logical reasoning and analytical ability
Decision-making and problem solving
General mental ability
Basic numeracy (numbers and their relations, orders of magnitude, etc. ). (Class X level), Data interpretation (charts, graphs, tables, data sufficiency etc. Class X level).

This is a complete list of UPSC optional subjects for civil services main examination. You have to opt for any one subject:Animal Husbandry and Veterinary Science
Anthropology
Botany
Chemistry
Civil Engineering
Commerce and Accountancy
Economics
Electrical Engineering
Geography
Geology
History
Law
Management
Mathematics
Mechanical Engineering
Medical Science
Philosophy
Physics
Political Science and International Relations
Psychology
Public Administration
Sociology
Statistics
Zoology
Literature of anyone the following language: Assamese, Bengali, Bodo, Dogri, Gujarati, Hindi, Kannada, Kashmir, Konkani, Maithili, Malayalam, Manipur, Marathi, Nepali, Oriya, Punjabi, Sanskrit, Santhali, Sindhi, Tamil, Telugu, Urdu, English. Agriculture
If you choose any subject here from the list you can reduce the time you invest for preparation of optional subject separately.

CBI recruits candidates through direct recruitment, deputation, promotion by seniority or through Limited Departmental Competitive Examination. All direct recruitment of Group C posts for sub-inspectors, constables and lower division clerk are made through Staff Selection Commission (SSC). Procedure to join in CBI as sub inspector:
Sub inspectors are recruited through SSC's Combined Graduate Level Examination (CGLE), followed by medical examination and personal interview. To join IB, you have to apply for the Combined Graduate Preliminary examination (CGPE). It's nothing but CGLE only. This exam is conducted by the SSC every year. The eligibility required for this examination is given below (at last in the answer). Education qualification:
To apply for this examination, a candidate should be graduate in any discipline from a recognized university. Those appear in the final year examination are also eligible. Age limit:
For the Intelligence Bureau (IB), candidate's age should be between 20 to 27 years. There is relaxation in age for the reserved category candidates like scheduled castes/ scheduled tribes.

CBI recruit candidates through direct recruitment, deputation, promotion by seniority or through Limited Departmental Competitive Examination. All direct recruitment of Group C posts for sub-inspectors, constables and lower division clerk are made through Staff Selection Commission (SSC). Procedure to join in CBI as sub inspector :
Sub inspectors are recruited through SSC's Combined Graduate Level Examination (CGLE), followed by medical examination and personal interview. To join IB, you have to apply for the Combined Graduate Preliminary examination (CGPE). It's nothing but CGLE only. This exam is conducted by the SSC every year. The eligibility required for this examination is given below (at last in the answer). Education qualification:
To apply for this examination, a candidate should be graduate in any discipline from a recognised university. Those appear in the final year examination are also eligible. Age limit:
For the Intellegence Bureau (IB), candidate's age should be between 20 to 27 years. There is relaxation in age for the reserved category candidates like scheduled castes/ scheduled tribes.