Which of the following does not represent a physical property of caffeine? Select one: a. Caffeine melts at 238C. b. Caffeine dissolves in water. c. Caffeine has a density of 1.23 g/mL. d. In the body, caffeine reacts with adenosine receptors in the central nervous system. e. Caffeine is a white powder. If the following operations are carried out, how many significant figures should be reported in the answer? (2.30) / (21.13 - 1.271) Select one: a 1 b. 2 c.3 d. 4 e. 5 Which statement is not correct? Select one: o a. Electrons have a negative electrical charge. O b. Protons have a positive electrical charge. c. Neutrons do not have an electrical charge. d. In an atom, the interaction between electrons and protons is attractive. O e. In an atom, the interaction between electrons and neutrons is repulsive. An As atom has protons, neutrons, and electrons. Select one: O a. 33; 33; 33 O b. 33; 44:33 O c. 33; 77; 33 O d.33; 44:44 O e. 44; 33; 77 ; The average atomic mass of zinc is 65.39 amu. Given the data in the following table, what is the natural abundance of 66Zn? Isotope Mass Natural (amu) Abundance (%) 63.9291 48.89 65.9260 2 67 Zn 66.9271 4.11 67.9249 18.56 69.9253 0.62 64 zn 66 zn 68 ZA 70 zn Select one: a. 27.83% b. 0.2783% c. 50.00% O d. 2.783% ( e. 28.73% Elements in group 16 (VIA) are called Select one: O a. alkali metals. b. transition metals b c. alkaline earth metals. d. halogens. e. the oxygen family