The tenure of the Prime Minister of India is not fixed by the Constitution. The Prime Minister is appointed by the President of India, who is the head of state, but the Prime Minister must have the confidence of the Lok Sabha, the lower house of Parliament. The Lok Sabha is directly elected by the people of India every five years, and if the Prime Minister loses the confidence of the Lok Sabha, they must resign.

In practice, this means that the Prime Minister's tenure is usually five years, but it can be shorter or longer. For example, Morarji Desai served as Prime Minister for only 2 years and 126 days, while Jawaharlal Nehru served for 16 years and 286 days.

The Prime Minister can also be removed from office by the President if they are found to be guilty of misconduct or if they are unable to carry out their duties. However, this has only happened once in the history of India, when Indira Gandhi was dismissed by President Fakhruddin Ali Ahmed in 1977.

The Prime Minister of India is the head of the government and has a wide range of powers, including the power to appoint and dismiss ministers, to introduce legislation, and to declare war. They are also responsible for overseeing the day-to-day running of the government.

The Prime Minister is a very powerful position in India, and they play a key role in shaping the country's policies and direction. The tenure of the Prime Minister is not fixed, but it is usually five years. The Prime Minister can be removed from office by the President if they are found to be guilty of misconduct or if they are unable to carry out their duties.

Here are some of the most notable Prime Ministers of India:

• Jawaharlal Nehru: Nehru was the first Prime Minister of India and served from 1947 to 1964. He is considered the "architect of modern India" and is credited with leading the country through its independence and early years.
• Indira Gandhi: Gandhi was the Prime Minister of India from 1966 to 1977 and again from 1980 to 1984. She is the only woman to have served as Prime Minister of India and is known for her strong leadership and controversial policies.
• Lal Bahadur Shastri: Shastri was the Prime Minister of India from 1964 to 1966. He is known for his role in the Tashkent Declaration, which ended the Indo-Pakistani War of 1965.
• Atal Bihari Vajpayee: Vajpayee was the Prime Minister of India from 1998 to 2004. He is the only person to have served as Prime Minister of India twice without being from the Congress Party.
• Manmohan Singh: Singh was the Prime Minister of India from 2004 to 2014. He is the first Sikh to have served as Prime Minister of India and is known for his economic reforms.

The Prime Minister of India is a powerful and influential figure who plays a key role in shaping the country's policies and direction. The tenure of the Prime Minister is not fixed, but it is usually five years. The Prime Minister can be removed from office by the President if they are found to be guilty of misconduct or if they are unable to carry out their duties.