Explanation:

• "World Hindi Day 2021: Hindi is considered to be the mother language of India."
• Hindi Day is celebrated every year on 14 September marking the declaration of Hindi language as one of the official languages of Union government of India. On 14 September 1949, Hindi was adapted as one of the official languages in India.
• Observances: Commemoration of luminaries in the field of Hindi literature
• Hindi Diwas is celebrated on the 14th of September, to commemorate the adoption of Hindi in Devanagari script as one of the official languages in different Hindi speaking states of India. Hindi was adopted as one of the two official languages of the Republic of India by Constituent Assembly of Indiadue to the efforts of Beohar Rajendra Simha along with Hazari Prasad Dwivedi, Kaka Kalelkar, Maithili Sharan Gupt and Seth Govind Das.As such, on the 50th birthday of Beohar Rajendra Simha on the 14th of September 1949, the efforts resulted in the adoption of Hindi as an official language.This decision was ratified by the Constitution of India that came into effect on the 26th of January 1950. "Under Article 343 of the Indian Constitution, Hindi written in Devanagari script was adopted as one of official languages. In all, there are 22 Scheduled languages of India."