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problem_pdfhw1chem301 - irshad(si2865 Homework 1...

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irshad (si2865) – Homework 1 – sutcliffe – (90830) 1 This print-out should have 25 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. REMEMBER: DO NOT ROUND NU- MERICAL QUESTIONS. ENTER AT LEAST FOUR SIGNIFICANT FIGURES. 001 10.0points Which of the following describes a chemical change? 1. alcohol evaporates 2. water is heated from 0 C to 50 C 3. wood is carved 4. gasoline burns in an engine 002 10.0points What is the volume of a sample of helium that has a mass of 2 . 48 × 10 3 g, and a density of 0 . 17847 g / L? Answer in units of mL. 003 10.0points What is the nuclear composition of an atom of iodine-131? 1. 53 protons, 78 neutrons 2. 131 protons 3. 53 protons, 53 electrons 4. 78 protons, 53 neutrons 004 10.0points How many hydrogen atoms appear in the for- mula of ammonium sulfate? 1. 6 atoms 2. 4 atoms 3. 10 atoms 4. 2 atoms 5. 8 atoms 005 10.0points Choose the pair of names and formulae that do not match. 1. KNO 3 : potassium nitrate 2. SCl 4 : sulfur tetrachloride 3. SnCl 4 : tin(V) chloride 4. N 2 O 3 : dinitrogen trioxide 5. MgSO 4 : magnesium sulfate 006 10.0points Which of the following is the molecular for- mula for heptane? 1. C 7 H 16 2. C 6 H 12 3. C 6 H 14 4. C 7 H 14 5. C 7 H 12 007 10.0points Calculate the energy of a photon of light with a wavelength of 0.37 km. 1. 2 . 5 × 10 31 J 2. 8 . 1 × 10 11 J 3. 2 . 5 × 10 34 J 4. 8 . 1 × 10 8 J 5. 5 . 4 × 10 23 J 6. 5 . 4 × 10 28 J 7. 5 . 4 × 10 25 J
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irshad (si2865) – Homework 1 – sutcliffe – (90830) 2 8. 5 . 4 × 10 22 J 9. 810000 J 008 10.0points We conduct an experiment by shining 500 nm light on potassium metal. This causes electrons to be emitted from the surface via the photoelectric effect. Now we change our source light to 450 nm at the same intensity level. Which of the following is the result from the 450 nm light source compared to the 500 nm source?
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