Yes, you can choose different languages for different papers in UPSC Mains.

The UPSC Mains examination consists of a total of nine papers, out of which two are qualifying in nature and the remaining seven are counted for merit. The two qualifying papers are on any modern Indian language and English. The seven papers that are counted for merit include Essay, General Studies I, General Studies II, General Studies III, General Studies IV, Optional Paper I, and Optional Paper II.

Choosing different languages for different papers:

1. Modern Indian Language Paper: This paper is of qualifying nature, and you can choose any one of the languages from the Eighth Schedule of the Constitution or English as the medium of writing. The languages available are Assamese, Bengali, Bodo, Dogri, Gujarati, Hindi, Kannada, Kashmiri, Konkani, Maithili, Malayalam, Manipuri, Marathi, Nepali, Odia, Punjabi, Sanskrit, Santali, Sindhi (Devanagari script), Tamil, Telugu, Urdu, and English.

2. English Paper: This paper is also of qualifying nature, and you are required to write an essay in English.

3. Essay Paper: You have the option to write the Essay paper in the language of your choice, which can be different from the language chosen for the Modern Indian Language paper or English.

4. General Studies Papers: The General Studies papers do not have any language requirement. You can choose to write them in the language of your choice, which can be different from the other papers.

5. Optional Papers: Similar to the General Studies papers, the Optional papers also do not have any language requirement. You have the flexibility to choose the language in which you are comfortable writing the Optional papers.

Important Points to Note:

- The choice of language for the Modern Indian Language paper and the English paper cannot be changed once selected during the application process.
- The choice of language for the Essay paper and the Optional papers can be different from the language chosen for the qualifying papers.
- It is advisable to choose a language in which you are proficient and can express your thoughts and ideas clearly.
- The UPSC provides question papers in various languages, but the answer scripts are to be written only in the language chosen for each paper.

In conclusion, you have the flexibility to choose different languages for different papers in the UPSC Mains examination. It is important to carefully consider your language proficiency and choose a language in which you can effectively communicate your ideas and thoughts to maximize your performance in the examination.