The relative atomic mass of an element is: A. the mass of its atoms co pared to the mass of a carbon-12 atom.

B. The mass of its atoms averaged over time.

C. The mass of its isotopes compared to the mass of a normal atom.

D. The mass of only the neutrons in the atoms nucleas.​

Which of these is the result of scientific research and not engineering? a. a new shoe design that features air cushioning for more comfort and protection b. the creation of glass with uv protection. c. a conclusion about diet commonalities among diabetics. d. the development of a smaller, more compact missile.

Iknow the answer is a but i don't know why

Which statement is true about the part of the electromagnetic spectrum that human eyes can detect? it contains only the colors of the rainbow and television waves. o it is divided into seven ranges of wavelengths. it contains ultraviolet, visible, and infrared light. it is divided into nine ranges of wavelengths.