84. Indium has atomic number 49 and atomic mass 114.8 g. Naturally occurring indium contains a mixture of indium-112 and indium-115 in an atomic ratio of approximately_____.
(A) 25/75
(B) 75/25
(C) 50/50
(D) 94/6
(E) 6/94

80. What is the product of the following reaction? (A)(B)(C)(D)(E)

81. There are many types of noise in instrumental analysis. Which of the following descriptions about the different noise types is INCORRECT? (A) line noise - noise that occurs at discrete frequencies (B) drift noise – low frequency noise caused by flickering or drifting of light intensity (C) Gaussian noise – noise amplitude is dependent on frequency (D) Johnson noise - random fluctuations of electrons in electronic devices (E) shot noise - noise that arises from random variation in the number of photons reaching the detector or small number of electrons and holes generated in a semiconductor

82. One of the optical components of a spectrophotometer that selects the wavelength to irradiate the sample can be called the _____.(A) polychromator (B) monochromator (C) beam splitter (D) light source (E) optode

83. What is the key functional group present in penicillins that is essential for their antibacterial activity? (A) amide (B) carboxyl group (C) B-lactam ring (D) ether (E) thiophene group

85. The OH radical disproportionates according to the elementary chemical reaction OH + OH → H2O + O. This reaction is second order in OH. The rate constant for the reaction is cm³/molecules at room temperature. If the initial OH concentration is molecules/cm³, what is the first half-life for the reaction? (A)(B) 0.030 s (C)(D) 3.9 s (E) 6.0 s

86. The equilibrium process CaCO3 = can be split into several equilibrium processes to give a more complete picture of calcium carbonate's solubility. Which of the following equilibrium equations does not play a role for calcium carbonate's solubility? (A) (B)(C)(D)(E)

87. For the reaction, CO2(g) + 2H2O(g) → CH4(g) + 2O2(g), AH° = 803 kJ, which of the following will increase K? (A) increasing the temperature of system (B) decreasing the number of moles of methane (C) increasing the volume of system (D) increasing the number of moles of CO2 (E) none of the above

88. The Figure on the right shows the phase diagram for a compound X. You wish to purify a sample of X that was collected at P = 1.0 atm and T = 100 by subliming it. In order to sublime the sample, you should _____.(A) increase T to 300 K and then lower P to 0.5 atm (B) abandon the attempt to sublime X (C) lower P to 0.5 atm and then increase T to 200 К (D) increase P to 1.5 atm and then increase T to 300 K (E) increase T to 300 K, keeping P = 1.0 atm

89. How many of the following electron configurations for the species in their ground state are correct? (A) 1 (B) 2 (C) 3 (D) 4 (E) none

90. What is the product of the following reaction? (A)(B)(C)(D)(E)