Important Days & Dates Quiz: Important Days in September and October

He was a philosopher and a teacher who became the first Vice President and the second President of India, and when his students wished to celebrate his birthday he asked that the day be kept for teachers instead.

On 14 September 1949 the Constituent Assembly decided that Hindi written in the Devanagari script would be an official language of the Union, a decision that later became Article 343 of the Constitution, and that date is kept every year as Hindi Diwas.

He was the engineer behind the Krishna Raja Sagara dam and the flood protection works of Hyderabad, served as Diwan of Mysore and was given the Bharat Ratna in 1955.

The day, formally the International Day for the Preservation of the Ozone Layer, marks the signing of the Montreal Protocol on 16 September 1987, the agreement under which countries agreed to stop using chlorofluorocarbons and other substances that thin the ozone layer.

International Literacy Day was declared by UNESCO in 1966 and has been observed every year since to remind governments of the work left in teaching people to read and write.

World Tourism Day has been observed on this date since 1980 by the World Tourism Organization, the United Nations body for tourism, and each year a member country hosts the main celebration with a chosen theme.

India observes the day as Gandhi Jayanti, and the United Nations adopted the same date in 2007 as the International Day of Non-Violence in recognition of the method of non-violent struggle that Gandhi used.

The Indian Air Force was raised on 8 October 1932 as an auxiliary force, and that date is kept every year as Air Force Day, usually with a parade and a fly past at an air force station.

World Food Day is kept on the anniversary of that founding, and it draws attention to hunger, nutrition and the security of the world's food supply.

The Charter of the United Nations, signed at San Francisco in June 1945, came into force on 24 October 1945 after it had been ratified by the required number of states, and the United Nations counts that day as the day it came into being.

As the first Deputy Prime Minister and Home Minister he brought the princely states into the Indian Union, which is why his birthday is kept as National Unity Day, with the Run for Unity held across the country.

He led the missile programme, was a key figure in the nuclear tests of 1998, served as the eleventh President of India and was given the Bharat Ratna in 1997.