Question

silicon ammonia fermentation iron 4 without , our computers and phones would not work

Explanation:

Silicon is a key element in the semiconductor industry used to make micro - chips in computers and phones. Without it, these devices wouldn't function. Ammonia is a compound mainly used in fertilizers and cleaning products, fermentation is a biological process, and iron is a metal used in construction and manufacturing but not a fundamental component for the operation of computers and phones like silicon.

Answer:

silicon