Final answer:
In Mozart's day, the use of low wind and brass instruments in his Requiem was standard practice.
Step-by-step explanation:
In Mozart's day, the use of low wind and brass instruments in his Requiem was indeed standard practice. The inclusion of instruments such as the tuba with long coiled tubes allowed the production of very low frequencies. As the Industrial Revolution progressed, improvements in the mechanical valves and keys of wind instruments led to better-tuned sounds and increased complexity in orchestral compositions.