A grand duchy named for which city was created by Napoleon in 1807 to partly restore the Polish state?

A graduate of Howard University, who won the Nobel Prize in Literature in 1993? What is a single grain or seed of an ear of corn called? Which grammatical case is abbreviated "nom."? A Grand Alliance was formed in 1689 against which French "Sun King"? How many legs does a grand piano normally have? A grandson of Man o' War, which horse beat War Admiral in a famous match race on November 1, 1938? A gravestone in London's Bunhill Fields marks the burial of which poet-painter who lived from 1757 to 1827? A great escape from Stalag Luft III in 1944 was through one of these nicknamed "Harry". What was it?