Explanation

Twenty viceroys ruled India.

Here is the list of Viceroys who ruled India, along with their duration period:

1. Lord Canning (1858–1862)
2. Lord Elgin (1862–1863)
3. Sir John Lawrence (1864–1869)
4. Lord Mayo (1869–1872)
5. Lord Northbrook (1872–1876)
6. Lord Lytton (1876–1880)
7. Lord Ripon (1880–1884)
8. Lord Dufferin (1884–1888)
9. Lord Lansdowne (1888–1894)
10. Lord Elgin II (1894–1899)
11. Lord Curzon (1899–1905)
12. Lord Minto (1905–1910)
13. Lord Hardinge (1910–1916)
14. Lord Chelmsford (1916–1921)
15. Lord Reading (1921–1926)
16. Lord Irwin (1926–1931)
17. Lord Willingdon (1931–1936)
18. Lord Linlithgow (1936–1943)
19. Lord Wavell (1943–1947)
20. Lord Mountbatten (1947)