I want to give IAS exam Papers in Bengali Language, can I do this???????????

No you can not give all IAS exam Papers in Bengali Language except the language papers. As the Civil services examination's question papers will be available in English and Hindi languages only. You can choose one of these languages. The language papers of IAS examination are as following:

Bengali
Bodo
Dogri
Gujarati
Hindi
Kannada
Marathi
Nepali
Oriya
Kashmiri
Konkani
Maithili
Malayalam
Manipuri
Punjabi
Sanskrit
Santali
Sindhi
Tamil
Telugu
Urdu