Article 345 of Constitution of India "Official language or languages of a State"
Subject to the provisions of Article 346 and 347, the Legislature of a State may by law adopt any one or more of the languages in use in the State or Hindi as the language or languages to be used for all or any of the official purposes of that State:
Provided that, until the Legislature of the State otherwise provides by law, the English language shall continue to be used for those official purposes within the State for which it was being used immediately before the commencement of this Constitution.
Article 346 of Constitution of India "Official language for communication between one State and another or between a State and the Union"
The language for the
time being authorised for use in the Union for official
purposes shall be the official language for communication
between one State and another State and between a State and
the Union:
Provided that if two or more States agree that the Hindi
language should be the official language for communication
between such States, that language may be used for such
communication.
Article 347 of Constitution of India "Special provision relating to language spoken by a section of the population of a State"
On a demand being made in that behalf the President may, if he is satisfied that a substantial proportion of the population of a State desire the use of any language spoken by them to be recognised throughout that State or any part thereof for such purpose as he may specify.