Hello Aspirant,

To become an Indian Administrative service (IAS) officer, you must qualify in the civil services examination conducted by the union public service commission (UPSC). This exam is conducted every year and recruits candidates to 25 different services including IAS, IPS, IRS etc. For the preliminary examination there will be two papers

Paper 1- 100 questions-200 marks 2 hours

• History
• Geography
• Polity
• General knowledge
• Sciences
• Economics
• Current affairs

Paper 2- 80 questions 200 marks 2 hours

• Mathematics
• Logical reasoning
• General English

You can find the entire information on the link provided below

https://www.google.com/amp/s/competition.careers360.com/exams/upsc-civil-services-exam/amp

Hope this helps and Good luck