Who is the constitutional head of government of india?
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Who is the constitutional head of government of india in 2017-current?
Ram Nath Kovind
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Who is the constitutional head of government of india in 2012-2017?
Pranab Mukherjee
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Who is the constitutional head of government of india in 2007-2012?
Pratibha Devisingh Patil Pratibha Patil
List of presidents of India
https://en.wikipedia.org/wiki/List%20of%20presidents%20of%20India
The president of India is the head of state of India and the Supreme Commander of the Indian Armed Forces. 
List of presidents of India
Pratibha Devisingh Patil[1] (born 19 December 1934) is an Indian politician who served as the 12th President of India from 2007 to 2012.
Pratibha Patil
Pranab Kumar Mukherjee (Bengali: প্রণব কুমার মুখার্জি; 11 December 1935 – 31 August 2020)[3][4][5][6][7][8] was an Indian statesman who served as the 13th President of India from 2012 until 2017.
Pranab Mukherjee
Ram Nath Kovind (born 1 October 1945) is an Indian politician serving as the 14th and current president of India since his inauguration in 2017.[2]
Ram Nath Kovind
The President of India is the head of state of India and the Supreme Commander of the Indian Armed Forces. Indian politician Pratibha Devisingh Patil served as the 12th President of India from 2007 to 2012. Pranab Mukherjee was an Indian statesman who served as the 13th President of India from 2012 until 2017. Ram Nath Kovind is an Indian politician serving as the 14th and current president of India since his inauguration in 2017.