What are functions of the labeled structures?

A:

B:

C:

D:

Which type of reaction always has an element and a compound as reactants

The wave shown on the electromagnetic spectrum disturb the medium it passes through a)different frequency. b)the same frequency .

The characteristics 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 an element. which statement is true about the atoms of the elements that participate in the two reactions? their identity changes in both reaction a and reaction b. their identity changes in reaction a but not in reaction b. their identity changes in reaction b but not in reaction a. their identity remains the same in both reaction a and reaction b.