Why does the engineering design process not move smoothly from step to step, but instead goes back and forth between the steps? i know this answer, lol but i don’t know how to explain it! this

Think about it like the scientific process you did in school. You test out your hypothesis, but if there is a problem, you are proven wrong, or something doesn't go as planned, you have to retrace your steps and retry.

Ok what do you need with

Answer///(d) atoms contain small,negatively charged particles;