Final answer:
The claim that Mussorgsky composed Pictures at an Exhibition after witnessing an artist during live composition is false; he was inspired by a posthumous exhibition of his late friend Viktor Hartmann's artwork.
Step-by-step explanation:
The statement that the Russian composer Mussorgsky was inspired to compose Pictures at an Exhibition after witnessing an artist during live composition is false. Modest Mussorgsky composed this suite in 1874 in honor of his friend, the artist Viktor Hartmann, who had recently died.
Mussorgsky's inspiration for Pictures at an Exhibition came from a posthumous exhibition of Hartmann's artwork, not from watching Hartmann create art live. The suite is famous for its musical depiction of various artworks by Hartmann, with each movement reflecting a particular piece of art or collection of works that Mussorgsky saw at the exhibition.