All of the following would be questions that could be scientifically investigated except:

"What is the best advice a parent can give a child?"

Explanation:

The other answers have one clear response. Ex: Orange popsicles melt faster than grape popsicles. That would be a fact.

But parental advice can vary, depending on your opinion. I may say that all parents must teach their children not to talk to strangers, while someone else may say that parents should advice their kids to treat everyone fairly. Nothing can be proven as the only appropriate response.

Hope this helps!

at right angles to each other

no. bullets are macro objects. wave nature is for light waves, extremely tiny particles. if a light particle was the size of your finger, the bullet would be the size of the universe. so basically, that huge difference in size makes the wave nature of matter insignificant.