Final answer:
Mozart's Symphony No. 40, IV, uses Sonata-allegro form with counterpoint as a featured element. The development starts pianissimo, contrasting with louder sections, and the textures are homophonic in the exposition and polyphonic in the development.
Step-by-step explanation:
Mozart’s Symphony No. 40 in G Minor, K. 550, IV is in Sonata-allegro form, addressing the question of the movement's structure. A prominent musical element from the Baroque period that features in the first theme is counterpoint, a technique characterized by the interplay of independent melodic lines.
At the beginning of the development section, the orchestra plays pianissimo, which contrasts with the dynamics of the rest of the movement and highlights changes in the music’s texture and intensity.
The texture of the music throughout the symphony varies, with the exposition being predominantly homophonic, showcasing a main melody with harmonic accompaniment. In contrast, the development section features a more polyphonic texture, with multiple lines of music interweaving.