複選題

2. Which of the following statements about normal distribution is (are) correct?

 (AB) Bell-shaped distributions are normal distributions. (AC) Approximately 95% of the area of a normal distribution is within three standard deviations of the mean. (AD) The median and mode are not equal for a normal distribution. (AE) Normal distributions can differ in their means and in their standard deviations. (BC) The average of many observations of a random variable with finite mean and variance is itself not a random variable. (BD) Normal distributions are often used in the natural and social sciences to represent real-valued random variables whose distributions are not known.

複選題1. Which of the following statements related to data treatment is (are) correct? (AB) The medium is the most common number in a data set. (AC) The coefficient of variation and relative standard deviation have the same value. (AD) The standard error ofthe mean is given by the standard deviation of the data set divided by the number of measurements. (AE) The mean is known with more confidence than is a single result. (BC) As the sample size increases, the confidence interval increases. (BD) As the standard deviation increases, the confidence interval decreases.

複選題3. Which of the following analytical statistics statements is (are) correct? (AB) A user repetitively reading the volume marking on the pipet from an angle rather than at eye level causes random error. (AC)Random error causes data to be scattered more or less symmetrically around a mean value.  (AD) The relative error of a measurement is the difference between the measured value and the true value divided by the standarddeviation. (AE) Systematic method errors can be decided by application of the method to the analysis of a standard reference material having one or more analytes at known concentration levels.  (BC) The mean is the middle result when replicate data are arranged according to increasing or decreasing value. (BD) Proportional systematic errors can be detected by varying the sample size.

複選題4. Which of the following statements about spectrophotometer is (are) correct? (AB) In a single-beam spectrophotometer, the solvent and solution are irradiated simultaneously or nearly so. (AC) A double-beam spectrophotometer employs a fixed beam of radiation that irradiates the solvent and the analyte solution sequentially. (AD) The single-beam spectrophotometer can be adapted to automatic spectral recording easier than the double-beam spectrophotometer. (AE) Problems arising from fluctuations in the source intensity due to drift in electronic circuits are less in double-beam spectrophotometers than single-beam spectrophotometers. (BC) Diode-array spectrophotometers can detect the entire spectral range essentially simultaneously and can produce a spectrum in less than a second. (BD) The resolution of diode-array spectrophotometers is usually higher than that of conventional spectrophotometers.

複選題5. Which of the following statements about molecular absorption and luminescence spectrometries is (are) correct? (AB) The dissociation, association, and reaction of analytes with the solvent will not cause deviations from Beer's Law. (AC) The most common source of visible and near-IR radiation is the deuterium/hydrogen lamp. (AD) The visible region includes the wavelength range between 200 and 300 nm.  (AE) A triplet state is one in which the spins of the electrons of an atom or molecule are paired so that their spin angular moments add to give a net non-zero moment. (BC) Resonance fluorescence is observed when an excited species emits radiation of the same frequency as that used to cause the excitation. (BD) Vibrational relaxation is the process by which a molecule loses its excess vibrational energy without emitting radiation.

複選題6. Which of the following statements about atomic spectrometry is (are) correct? (AB) An ionization suppressor is more easily ionized than the analyte and provides a high concentration of electrons in the flame or plasma. (AC)Pressure broadening refers to the broadening of atomic lines due to sample vaporization and decomposition.  (AD)One single lamp is used in flame atomic absorption for analyzing different elements.  (AE)An x-ray source is a tube filled with low-pressure argon in which a tungsten filament cathode and a massive anode aremounted.  (BC)Atomic emission methods with an ICP source is suited for multielement analysis.  (BD) A scintillation counter is an instrument for detecting and measuring non-ionizing radiation by using the excitation effectof incident radiation on a scintillating material.

複選題7. Which of the following statements about mass spectrometry is (are) correct? (AB) An electron multiplier is a vacuum-tube structure, in which a secondary emission process takes place and a single charge can bombard on secondary-emissive material and induce emission of several ions. (AC) Among different ion sources for molecular mass spectrometry, the most fragmentation is encountered with electron ionization, which does not produce the most complex spectra, though. (AD) The selection of sample ions in the quadrupole mass analyzer for detection is only made possible through applying a radio frequency voltage to one fixed pair of rods and a de offset voltage to the other. (AE) An electric voltage and a magnetic field are needed in both FT ICR and TOF mass spectrometers. (BC)The resolution of a quadrupole is determined by the ratio of the ac to dc voltage and becomes a maximum when this ratiois just slightly less than 6. (BD)ICPMS uses an inductively coupled plasma to separate ions and a mass spectrometer to detect them.

複選題 10. Which of the following description is correct? (4%) (A) The solubility product constant (Ksp) of aluminum hydroxide (Al(OH)3) is 3 ×10-34; the Ksp of cadmium sulfide (CdS) is 1× 10-27. Based on this information, we know that Al(OH)3 is less soluble than CdS in pure water. (B) A glass of aqueous solution (100 mL) contains [Ca2+] = 2.13✖10-4 M, [F-] = 4.26✖ 10 -4 M, and 0. 781 g of insoluble Caf2 solid. Based on this information, we can estimate the Ksp of Caf2 to be ~3.9 x 10-11 (C) Even through the same chemical can sometimes exist in more than one crystalline form, e.g., CaCO3 can be both calcite and aragonite, they are always equally soluble. (D) The pKa1and pKa2 of methionine are 2.28 and 9.21. Based on this information, we know that methionine has the best buffering power (capacity) at pH 5.75 (the mid-point between the two pKa values). (E) The hydrogen cation concentration ([H+]) of a pH 6.5 solution is 5.0 ✖10-7 M. 

9.Graphs shown below are data obtained by the following analytical methods (from left to right): IR, NMR, EPR, and MS. What are the correct x-axis labels and units? (4%) (A) Micrometer (um) - magnetic field (MHz) - magnetic field (G) - atomic mass unit (Da) (B) Wavenumber (1/cm) - magnetic field (MHz) - magnetic field (G) - atomic mass unit to charge ratio (Da/z) (C)Wavenumber (1/cm)- chemical shift (ppm) - magnetic field (G) - atomic mass unit to charge ratio (Da/z) (D)Micrometer (μm) - chemical shift (ppm)- Coulomb （C） - atomic mass unit (Da) (E)Wavenumber (1/cm) -chemical shift (ppm)- resistance (Ω) - atomic mass unit (Da)

8. All of the following are spontaneous reactions that proceed to the right. Standard reduction potentials at 259C are provided for some half-cell reactions. Based on this information, rank the relative strengths of H+, Ag+ , Cd2+, Cu2+, and Zn2+ as electron acceptors (oxidizing agents) at 25℃. (4%) (A) Cu2+ ＞ H+＞Ag+ ＞ Cd2+＞Zn2+ (B) Ag+＞ Cu2+＞H+> Cd2+＞Zn2+ (C) Zn2+＞ Cd+＞Ag+＞ Cu2+＞H+ (D)Zn2+＞ Cd+＞ H+＞Ag+ ＞ Cu2+(E) There is not enough information to deduce their relative oxidative strengths.

7. Which of the following description about various forms of light emission is NOT correct? (4%) (A) Fluorescence and phosphorescence signals are typically measured at a 90° angle to the excitation beam. (B) In fluorescence spectra, the emitted radiation usually has a longer wavelength than the excitation radiation; this difference is called the Stokes shift. (C)The average lifetime of an excited triplet state is orders of magnitude shorter than that of an excited singlet state. (D)Chemiluminescence occurs when a chemical reaction generates an electronically excited species; this excited molecular species then emits light as it relaxes to the ground state. (E)Chemiluminescence is usually measured without selecting a specific wavelength for detection.

110年 - [無官方正解]110 國立臺灣大學_碩士班招生考試_化學研究所化學組:物化分析#129041

109年 - 109 國立台灣大學_碩士班招生考試：物化分析#90697