2006 final answers

2006 final answers - Final Exam Version A Chem 1B 1 Which...

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1 Final Exam, Version A, Chem 1B 1. Which is the smallest object that has been successfully detected as an image with an electron microscope? a) An HIV virus b) Pb atoms in crystalline lead c) C atoms in teflon d) Li ions in LiCoO 2 ANSWER D e) H atoms in H 2 2. What fundamental property of electrons enables electron microscopes to detect images of much smaller objects than optical microscopes can detect? a) Electrons are particles and photons are waves b) Electrons have wavelengths that are much longer than visible photon wavelengths c) Electrons have wavelengths that are much shorter than visible photon wavelengths ANSWER C d) Much higher densities of electrons can be used to form the image than is possible with photons. e) Higher vacuums can be produced in electron microscopes than in optical microscopes. 3. What effect does the intensity of the light used to irradiate the metal surface of the cathode have on measurement of the photoelectric effect? a) Higher intensities cause more current to flow in a photocell when the light frequency is higher than the threshold frequency. b) Higher intensities have no effect when the light frequency is lower than the threshold frequency. c) Higher intensities have no effect when the wavelength of light is longer than the wavelength of light whose energy is equal to the binding energy of electrons to the surface of the metal d) All of the above, a, b, and c, are correct ANSWER D e) None of the above 4. What change occurs in a hydrogen atom when an electron moves from the n = 2 level to the n = 4 level? a) The atom emits a photon and its internal energy, Е , increases b) The atom absorbs a photon and its internal energy, Е , increases ANSWER B c) The atom emits a photon and its internal energy, Е , decreases d) The atom absorbs a photon and its internal energy, Е , decreases e) The internal energy of the atoms, Е , does not change.
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2 5. Who is credited with developing the theory that explains the photoelectric effect? a) Max Planck b) Albert Einstein ANSWER B c) Werner Heisenberg d) Erwin Schrödinger e) Niels Bohr 6. Which of the following stars has the highest temperature? a) One that appears white to the eye b) One that appears red to the eye c) One that appears orange to the eye d) One that appears blue to the eye e) One that appears violet to the eye ANSWER E 7. When a single color of light is passed through two slits that are parallel to each other and the light from the two slits is projected on a screen, you see a pattern of lighted and dark areas on the screen. What phenomenon causes this pattern to appear? a) Particles of light (photons) from the two slits run into each other and are deflected away from where the dark areas appear. b)
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This note was uploaded on 04/07/2008 for the course CHEM 1B taught by Professor Watts during the Winter '08 term at UCSB.

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2006 final answers - Final Exam Version A Chem 1B 1 Which...

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