Hi there!

UPSC exam for becoming an IAS requires two optional subjects to be attended. Each optional paper bears 250 marks. Optional paper 1 can be selected as per your capacity and interest. It may or may not be the subject of your graduation. Optional paper 2 is based on any regional language subject.

So both the papers are mandatory.

Hope this helps!

There are two compulsory papers of 200 marks each in the Civil Services Prelims Exam.

Paper-I

Section 1 Essay 200 Marks

Section 2 English Comprehension & English 100 Marks    (The level of paper would be Matriculation/ Xth standard   level)

Paper-II

General Studies–I 250Marks    (Indian Heritage and Culture,   History and Geography of the World     and Society)

Paper-III    General Studies –II 250 Marks    (Governance, Constitution,   Polity, Social Justice and   International relations)

Paper-IV    General Studies –III 250 Marks   (Technology, Economic Development,   Bio-diversity, Environment, Security   and Disaster Management) Paper-V    General Studies –IV 250 Marks    (Ethics, Integrity and Aptitude)

Paper-VI    Optional Subject – Paper 1 250 Marks

Paper-VII    Optional Subject – Paper 2 250 Marks

Rest details you can check here: Civil exam paper

Good Luck.