AP Biology Chapter 2 review

4. Which statement is true of all atoms that are anions? A. the atom has more electrons than protons B. the atom has more protons than electrons C. the atom has fewer protons than does a neutral atom of the same element D. the atom has more neutrons than protons E. the net charge is 1-

A. the atom has more electrons than protons

1. In the term *trace elements* the adjective *trace* means that A. the element is required in very small amounts B. the element can be used as a label to trace atoms through an organisms metabolism C. the element is very rare on earth D. the element enhances health but is not essential for the organisms long-term survival E. the element passes rapidly through the organism

A. the element is required in very small amounts

3. The reactivity of an atom arises from A. the average distance of the outermost electron shell from the nucleus B. the existence of unpaired electrons in the valence shell C. the sum of the potential energies of all the electron shells D. the potential energy of the valence shell E. the energy difference between the *s* and *p* orbitals

B. the existence of unpaired electrons in the valence shell

5. Which of the following statements correctly describes any chemical reaction that has reached equilibrium? A. the concentrations of the products and reactants are equal B. the reaction is now irreversible C. both forward and reverse reactions have halted D. the rates of the forward and reverse reactions are equal E. no reactants remain

D. the rates of the forward and reverse reactions are equal

2. Compared with "P", the radioactive isotope "P" has A. a different atomic number B. a different charge C. one more proton D. one more electron E. one more neutron

E. one more neutron