Listen to Six Pieces on One Theme, Op. 21: III. Impromptu. Allegro molto online. Six Pieces on One Theme, Op. 21: III. Impromptu. Allegro molto is an Instrumental language song and is sung by Michael Ponti. Six Pieces on One Theme, Op. 21: III. Impromptu. Allegro molto, from the album 111 Tchaikovsky Masterpieces, was released in the year 2012. The duration of the song is 1:46. Download Instrumental songs online from JioSaavn.