The last viceroy of India was not Lord Mountbatten.
Louis Mountbatten (1900-1979) was India’s last British viceroy, or governor general, from August 1947 to June 1948.
Chakravarti Raj agopalachari (1879-1972) then served as governor-general of India’s interim government from June 1948 to January 1950, when the position was abolished.