27. Which of the following methods concerning high-performance liquid chromatography (HPLC) are INCORRECT?
(A) Ion-pair chromatography is powerful for the separation of metal ions due to the addition of ion- pair reagents.
(B) Size-exclusion chromatography is useful for the separation of large-sized macromolecules, but it suffers from limited resolution and long analysis time
(C) In reversed-phase HPLC, polar analytes elute carlier than nonpolar ones.
(D) In ion-exchange chromatography, ion exchangers bind preferably ions of higher charge and increased hydrated radius

23. Which of the following statements concerning surface spectroscopic methods are INCORRECT? (A) X-ray photoelectron spectroscopy is useful to identify the elemental composition of the sample and determine its valance state. (B) The elemental hydrogen in the sample can be detected by X-Ray photoelectron spectroscopy. (C) The process of Auger electron spectroscopy (AES) includes atomic ionization, electron emission, and analysis of the emitted Auger electrons (D) In X-Ray photoelectron spectroscopy, detection limits for most of the elements are in the parts per thousand range.

24. Which of the following statements concerning inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass-spectrometry (ICP-MS) are INCORRECT? (A) ICP-OES can be used to analyze isotopes of elements (B) ICP-MS is more sensitive than ICP-OES (C) The steps associated with ICP-MS analysis of the samples include introduction-atomizing, ionization, mass separation, and detection (D) ICP-OES and ICP-MS both provide high throughput multi-element analysis.

25. The activity coefficients of H+ and OH- are 0.83 and 0.76 when the ionic strength is 0.1. The pH of water containing 0.10 M LiNO3 at 25℃ are (A) 6.98 (B) 7.00. (C) 7.02 (D) 7.04

26. Which of the following statements concerning gas chromatography (GC) are INCORRE CT? (A) The split injection is selected when the concentration of the target analyte in the sample is at trace level. (B) GC combined with a flame-ionization detector is used extensively for the detection of hydrocarbons. (C) GC in conjugation with a thermal-conductivity detector is useful for the analysis of a mixture of gases (D) A polydimethylsiloxane-based polymer is heavily used as a stationary phase in GC.

28. Which of the following methods concerning absorption are INCORRECT? (A) UV-Visible spectroscopy of organic compounds is usually associated with n → π*and π → π*(B) The intensity of absorbance is proportional to the log of the absorbing species concentration (C) An atomic absorption spectrum consists of a series of line peaks (D) X-ray absorption spectroscopy (XAS) can probe the chemical surroundings around an atom of interest.

29. Which of the following statements concerning fluorescence are INCORRECT? (A) The lifetime of fluorescence is s. (B) The difference between the excitation and emission wavelengths is called the Stokes Shift. (C) Fluorescence intensity is sensitive to environmental factors, such as pH and solvent polarity. (D) The fluorescent quantum yield is dependent of excitation intensity.

30. Which of the following statements concerning gravimetric methods are INCORRECT? (A) The particle size of a precipitate can be enhanced by minimizing the relative super-saturation during precipitate formation (B) An electric double layer consists of the primary adsorption layer and counter-ion layer. (C) Peptization is a process in which a precipitate is beated in the mother liquor. (D) A gravimetric volatilization method is the classical method for the determination of hydrogen and carbon in organic compounds

1. DNA-binding proteins primarily recognize a specific sequence of double-stranded DNA through_________. (A) interactions with the exposed chemical groups in the DNA sugar-phosphate backbone (B) interactions with the exposed chemical groups in the minor groove of the DNA (C) interactions with the exposed chemical groups in the major groove of the DNA (D) attraction between the protein and negative charges on DNA

2. Which one of the following statements about the structure of RNA is NOT true? (A) RNA is capable of forming secondary structure. (B) RNA is capable of forming tertiary structure. (C) RNA is capable of forming pseudoknots. (D) RNA is capable of forming B-sheets.

3. Consider an experiment in which nucleic acids are separated using agarose gel electrophoresis. In the gel you load the following samples: Lane 1: a population of linearized 3000-bp double-stranded DNA (dsDNA) molecules. Lane 2: a population of circular 3000-bp double-stranded DNA (dsDNA) molecules Which population of nucleic acids would most likely migrate through the gel fastest, and in which direction through the gel will these molecules migrate? (A) The linearized dsDNA would most likely migrate faster than the circular dsDNA. AlI DNA molecules would migrate toward the positive end of the gel. (B) The linearized dsDNA would most likely migrate faster than the circular dsDNA. AIl DNA molecules would migrate towards the negative end of the gel. (C) The circular dsDNA would most likely migrate faster than the linearized dsDNA. All DNA molecules would migrate toward the positive end of the gel. (D) The circular dsDNA would most likely migrate faster than the linearized dsDNA. All DNA molecules would migrate toward the negative end of the gel