3/31/2022 Quiz: CHEM3120/3920 In Semester Test https://canvas.sydney.edu.au/courses/38944/quizzes/170711/take 1/9 CHEM3120/3920 In Semester Test Started: Mar 31 at 23:25 Quiz Instructions CHEM3120/3920 In-Semester Test For information about this test (also referred to as quiz), please check the recent announcements. This online quiz covers material presented in Week 1-5, i.e. lectures 1 to 10 inclusive. The quiz consists of 10 multiple choice questions and 5 short answer questions and is worth 10% of your final unit grade. You are allowed 25min for the quiz which can be taken once only any time between 9am Monday March 28 and 5pm Friday April 1. The quiz is open book and you can refer to your lecture notes during the quiz. Students are advised, however, not to rely entirely on being able to search through their notes for every question. The quiz consists of 15 questions to be answered in 25 mins so time management is important. This is an individual task. You may not communicate with anyone else during the quiz. You may not transmit information about the questions to anyone else or seek assistance from anyone else. Please direct any inquiries to the Unit Coordinator Prof Brendan Kennedy bendan.kennedy@sydney.edu.au 1 ptsQuestion 1 32 mls 3.2 mls 320 mls 0.032 mls 0.32 mls 32 pph corresponds to how many mls per L 1 ptsQuestion 2 3/31/2022 Quiz: CHEM3120/3920 In Semester Test https://canvas.sydney.edu.au/courses/38944/quizzes/170711/take 2/9 A dose of 5 mg of compound X for each rat will kill half of the sample population. A dose of 1 mg of compound X for each rat will kill half of the sample population. A dose of 5 mg of compound X for each rate will kill 50 members of the sample population. A dose of 1 mg of compound X for each rate will kill 50 members of the sample population. A dose of 5 mg of compound X for each rat will kill 1/20th of the sample population. A compound X has an LD = 5 mg/kg when tested on a population of rats whose individual masses where all close to 0.2 kg. Which one of the following statements is correct 50 1 ptsQuestion 3 Contribute to the destruction of stratospheric ozone. Absorb some of the visible radiation emitted by the Earth. Absorb some of visible radiation from the Sun. Absorb some of the infrared radiation from the Sun. Absorb some of the infrared radiation emitted by the Earth. The most important role of gases like CO and CH in the Greenhouse Effect is to (select one option that correctly complete this sentence) 2 4 1 ptsQuestion 4 The mesosphere is 28-100 km above the Earth’s surface and so is very cold. Only greenhouse gases can absorb radiation and their concentration is low in the The temperature decreases as we move down through thermosphere into the mesosphere. Which one of the following explanations of this decrease in temperature is correct 3/31/2022 Quiz: CHEM3120/3920 In Semester Test https://canvas.sydney.edu.au/courses/38944/quizzes/170711/take 3/9 mesosphere The intensity of the solar radiation in the far UV decreases with decreasing altitude. The pressure increases which results in a cooling effect. The blackbody radiation from Earth occurs in the upper atmosphere which results in a cooling due to energy loss to space. 1 ptsQuestion 5 The Milankovitch cycles refer to periodic variation s in the Earth’s orbit The Milankovitch cycles refer to the recycling of carbon and nitrogen through the biopshere. The Milankovitch cycles refer to periodic increases in the temperature of the Sun The Milankovitch cycles make no contribution to the current global warming event. The Milankovitch cycles do not account for global warming events at any time in the Earth’s history Which one of the following statements about the Milankovitch cycles is correct 1 ptsQuestion 6 Quenching of the excited products is reduced by the addition of ozone. Quenching of the excited products results in a decreased fluorescence signal. It is only the fluorescence from the NO molecule that is measured. The role of ozone is to convert NO molecules into NO. The concentration of the ozone is not important as the method is designed to measure the concentration of NO . Which one of the following statements about the chemiluminescence detection of NO molecules is correct x x x 3/31/2022 Quiz: CHEM3120/3920 In Semester Test https://canvas.sydney.edu.au/courses/38944/quizzes/170711/take 4/9 1 ptsQuestion 7 The symbol applies to strong acids like hydrochloric acid. The symbol applies to strong oxidants capable of corroding iron. The symbol indicates that spills may require chemical treatment. The symbol indicates that care is required in choice of containers. The symbol applies to strong bases like sodium hydroxide. Which one of the following statements about this safety symbol is incorrect 1 ptsQuestion 8 281K 269K After an Ice Age, the albedo of Earth decreases due to decreased reflection from the ice. A simple energy balance equating the energy in and energy out (neglecting the greenhouse effect) estimated the Earth’s Ice Age temperature to be 248K with an albedo of 0.42. What would be the value of the estimated surface temperature if the albedo was decreased to 0.20 [Data: Rate of solar energy absorption by planet of radius R = F πR (1-A ) Rate of black body radiation = σT 4 πR Stephan-Boltzmann constant σ = 5.67 x 10 Wm K . The solar flux on Earth is 1480 Wm .] flux 2 albedo 4 2 -8 -2 -4 -2 3/31/2022 Quiz: CHEM3120/3920 In Semester Test https://canvas.sydney.edu.au/courses/38944/quizzes/170711/take 5/9 248K 276K 260K 1 ptsQuestion 9 N O CO OH NO O Which one of the following species is a radical 2 – 3 1 ptsQuestion 10 CO was converted to oxygen by photosynthesizing organisms. CO is a greenhouse gas and so undergoes fixation. CO was converted to methane by aerobic bacteria. CO is light enough to escape into space. CO dissolved in the oceans The concentration of CO in the early Earth atmosphere decreased substantially around 4 billion years ago. Which one of the following reasons accounts for this decrease 2 2 2 2 2 2 2 ptsQuestion 11 3/31/2022 Quiz: CHEM3120/3920 In Semester Test https://canvas.sydney.edu.au/courses/38944/quizzes/170711/take 6/9 When a hospital started receiving significantly more patients with symptoms linked to heavy metal poisoning, scientists gathered groundwater samples from the area to evaluate the source of the contamination and the severity of it. Propose a useful analytical tool for their task. Briefly explain your choice. 2 ptsQuestion 12 3/31/2022 Quiz: CHEM3120/3920 In Semester Test https://canvas.sydney.edu.au/courses/38944/quizzes/170711/take 7/9 In the spectrum of infrared emission from Earth observed from a satellite (the solid line in the plot shown above) there are a number of wavelengths at which the emission intensity is depleted when compared with the spectrum expected from a black body (the dashed curves). The asymmetric stretch of CO absorbs at a wavelength of 4.2μm. Explain briefly, with reference to the plot above, why this absorption does not contribute significantly to the Greenhouse Effect. 2 2 ptsQuestion 13 Aerosols are typically solid particles that can stay suspended in the atmosphere for long times. Provide a brief explanation of the competing physical effects that determine how long a particle can remain suspended in the air. 3/31/2022 Quiz: CHEM3120/3920 In Semester Test https://canvas.sydney.edu.au/courses/38944/quizzes/170711/take 8/9 2 ptsQuestion 14 Briefly describe one benefit and one negative impact arising from the use of industrially-fixed nitrogen fertilizers. 3/31/2022 Quiz: CHEM3120/3920 In Semester Test https://canvas.sydney.edu.au/courses/38944/quizzes/170711/take 9/9 Not saved 2 ptsQuestion 15 NO , a bent triatomic, has three vibrational modes. Describe the three modes and indicate which of these modes are infrared active. 2 Submit Quiz
