Question

How does grieg use dynamics, timbre, pitch, and tempo to achieve unity and variety in the piece "in the hall of the mountain king"

Answer 1

It starts slowly, with only a few instruments. Gradually speeds up the tempo, gradually gets louder, adding more instruments....but the same tune is repeated over and over again. The single the,e achieves unity. The tempo and dynamic changes (Loudness, speed) give is the variety.