The answer is Acharya Kripalani.
Acharya Kripalani was a freedom fighter, politician, and educationist. He was the President of the Indian National Congress from 1947 to 1948. He was also the Governor of Maharashtra from 1956 to 1962.
C.V. Raman was a physicist who won the Nobel Prize in Physics in 1930 for his discovery of the Raman effect. He was the first Indian to win a Nobel Prize.
Rajagopalachari was a freedom fighter, politician, and writer. He was the first Governor-General of independent India from 1947 to 1950. He was also the Chief Minister of Madras Presidency from 1937 to 1939 and from 1952 to 1954.
Radhakrishnan was a philosopher, statesman, and diplomat. He was the second President of India from 1962 to 1967. He was also the Vice President of India from 1952 to 1962.
The word that is different from the rest is Acharya Kripalani. The other three words are all politicians who served in high-ranking positions in the Indian government. Acharya Kripalani was a freedom fighter and educationist who did not serve in the government.