All of the following are characteristics of exchange systems except: select one: a. they pay special attention to calories. b. they give a sense of which foods are similar to each other. c. they sort foods by their carbohydrate contents only. d. they highlight the fact that most foods provide more than just one energy nutrient.

b..

is the correct one

explanation:

covalent bonds form as valence electrons are shared between two atoms. lewis structures and structural formulas are common ways of showing the covalent bonding in organic molecules. formal charge describes the changes in the number of valence electrons as an atom becomes bonded into a molecule.

the answer is 303.15 or 303