Chelsea thinks that in order to find the atomic mass shown for each element on the periodic table, scientists took the average of the masses of all of that element's isotopes. Is she correct or incorrect? Why?

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.

This classification of drug typically changes the brain's chemistry and reduces its ability to create its own endorphins.

The characteristic of two different types of reactions are shown below. reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of and element. which statement is true about the atoms of the elements that participate in the two reactions? a: their identity changes in both reaction a and b. b: their identity changes in reaction a but not b. c: their identity changes in reaction b but not a. d: their identity remains the same.