the official language of the union is Hindi

THE OFFICIAL LANGUAGE OF THE  UNION SHALL BE HINDI.

As provided under article 343(1) The official language of Union shall be Hindi is Devanagari Script but the form of numericals to be used for the official purpose of union Shell be the international form of Indian number details however ,the Article 343(3) state that for a of period of 15 years from the commencement of the constitution the English language shall continue to be used for the official purpose of union. Even after  15 years, the parliament may by law provide for the use of English language for specified purposes. It is further provided that even during this period of 15 years, the president may Authorize  the use of the Hindi language, in addition to the English language and of the devanagri forms of numericales for any official purposes of the union.

According to Article 345 of constitution which provides that the Legislature of the state may,by, law, and of anyone or more  of the language in use in the state or Hindi as language or other language to be used for all  or any of official purpose of that State.

According to Article 351 the central government is duty bound to promote the spread  of the Hindi language to develop it so that it may serve a medium of expression for all the elements of composite culture of India and to secure its enrichment by  assimilating, without interfering with its genus the forms style and expressions used in Hindustani and in other language of India by drawing for its vocabulary primarily from Sanskrit and  secondarily  from other language.

Article 348 of the constitution provides that the Parliament may also enact law for the use of Hindi language in the proceedings of Supreme Court and high courts .Under article 341(2)  the governor of the state with previous consent of the president may authorize the use of Hindi language or any other language to be used in proceeding before the High Court.

According to article 350 (a) :- 

The constitution every state is is duty bound to provide adequate facilities for instructions in the mother tongue at the primary stage of education for children belonging to linguistic  minorities  group. Under Article 350 (B),the president shall appoint a special officer for linguistic  minorities who will investigate all matter relating to to the safeguards provided for linguistic minorities  under the constitution and report to the president upon those matter as the President may direct .

Article 347 provides If a demand is made and President is satisfied that a substantial   proportion of the population of a state desire the use of any language spoken by them to be recognized by that States, he may direct that such  language shall also be officially recognized in  that state for such purpose  as he may specify.

However, Article 350 of the constitution gives rise to have a person to submit a representation for the redress of any reference to any officer of authority of the central government for the state government in any of the language used in union or in the state as the case may be.

The development of the Hindi and any other regional language the constitutional of India, 1950 article 344 for the appointment of a Commission on official language. The commission is required to make recommendation to the president of the following matters:-

1. Progressive use of Hindi language for the official purpose of the union,
2. Restrictions on the use of the English language for all or any of the official purpose of the union,
3.  The language to be used for all or any of the purposes mentioned in article 348,
4. The form of numericals to be used for any one or more specified purposes of the union,
5. Any other matter referred to the commission by the president as regards the official language of Union and the language for communication between the Union and the state or between one state and another and their use.

 article 344 (3 ),states that in making their recommendation under article 344 (2),to the commission shall have due regard to the industrial,cultural and scientific advancement of India, and the just claims and the interests of persons belonging to the non-Hindi speaking areas in regards to the public services.