Why Are Blood Vessel Called The Highway System Of The Body?

Because they are transporting nutrients, hormones etc to different parts of the body, quite similar to a highway where all cars are going within different directions like cities.

Resolved Questions:
Element X Exists As A Non Polar Molecule Made Of Two Identical Atoms....
Element X sounds like Oxygen, which is a group 7A element.

How Long Does It Take The Earth To Rotate On Its Axis?
24 hours (1 day) No it would be 365.24219 days - but that would be an Earth year, the period it takes to rotate around the sun. The time to spin on its axis is 24 earth hours 24 hours or...

What Are Organic Molecules?
All organic molecules are composed of carbon and hydrogen. They naturally exist in make-up. They are found in all living things and organic molecules are made up of proteins, carbs, amino acids and lipids(fat). Hope that help.. =)