16. The bactericidal concentration of phenol is

A. 0.25%
B. 0.5%
C. 0.75%
D. 1%

17. Which of the following is most effective for sterilizing mattresses and plastic petri plates?

A. Chlorine
B. Ethylene oxide
C. Glutaraldehyde
D. Ultraviolet radiation

18. Which of the following skin disinfectant(s) is/are most frequently used?

A. Isopropyl alcohol
B. Ethyl alcohol
C. Both (a) and (b)
D. none of these

19. All of the following are sporicidal except

A. glutaraldehyde
B. ethylene oxide
C. formaldehyde
D. alcohol

20. Which of the following describes the effect of ionizing radiation on microbes?

A. Changes the 3-dimensional structure of proteins to a 2-dimensional form
B. Substantially decreases enzymatic activity, slowing microbial reproduction
C. Induces electrons and protons to jump out of the molecules of the microbe
D. None of the above