Quiz 2

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University of Massachusetts, Lowell *

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1210

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Chemistry

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Jan 9, 2024

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Name: _________________ Quiz 2 Molar Mass = Mass/mole 1 mole = 6.02x10 23 E=hν λ =h/mv h: 6.6x10 -34 Js c= 3.00x 10 8 m/s c= λν 1m = 10 9 nm 1. (2 points) Which of the following experiment proves that most of space in atom is empty space? a. Cathode Ray b. Millikan oil drop c. Gold foil d. None of above 2. (2 points) Which of the following contains the fewest atoms? a. 10g of Mg b. 10g of Ca c. 10g of He d. 10g of Hg 3. (2 points) What is the mass of 8.37 x 10 23 He atoms? a. 5.55g b. 11.1g c. 1.39 g d. 20.5g 4. (2 points) Calculate the wavelength in meters of electromagnetic radiation that has a frequency of 980.0 kHz. (c = 3.00 X 10⁸ m/s), 1Hz = s -1 a. 2.94 x 10 11 m b. 2.94 x 10 14 m c. 3.06 x 10 7 m. d. 306.1m. 5. (2 points) and containing (a) the same number of neutrons, (b) the same number of protons, (c) the same number of nucleons, (d) the same total number of subatomic particles 6. A photon has a frequency of 8.63 × 10⁸ Hz. What is the energy of this photon in Joules? a. 7.68 J b. 5.72 × 10⁻²⁵ J c. 1.30 x 10 42 J d. 1.30 x 10 -26 J 7. (6 points) Determine the numbers of protons, neutrons, electrons and nucleon respectively, in each of the following: a. Ca +2 b. Se c. Ga Mass number: Ca: 41, Se: 79, Ga: 70 Atomic number: Ca: 20, Se: 34, Ga: 31 Proton neutron electron Nucleon Ca 20 21 18 41 Se 34 45 34 79 Ga 31 39 31 70 O 18 8 F 19 9

Name: _______________________ 8. (4 points) What is the de Broglie wavelength(in nm) of an electron traveling at 3.21×10 4 m/s? Mass of electron is 9.1 x 10 -31 kg. No work no credit λ = 6.6x10 -34 J.s/(9.1 x 10 -31 x 3.21×10 4 ) = 2.27 x 10 -8 m = 22.7nm 9. In photoelectric effect experiment, electron escaped from the metal with 1.87 x 10 6 m/s of speed. The binding energy of electron is 3.7ev. What is the frequency of the light? Mass of electron is 9.1x10 -31 kg, 1ev= 1.6x10 -19 J, 1kg = 1000g, 1m = 10 9 nm, Kinetic energy = ½ mv 2 E= BE + KE BE = 3.7 x 1.6 x 10 -19 = 5.9 x 10 -19 J KE = ½ x 9.1x10 -31 x (1.87 x 10 6 ) 2 = 1.6 x 10 -18 J E = BE + KE = 2.2 x 10 -18 J = hν ν = 3.3 x 10 -15 s -1

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Name: _________________ Quiz 2 Molar Mass = Mass/mole 1 mole = 6.02x10 23 E=hν λ =h/mv h: 6.6x10 -34 Js c= 3.00x 10 8 m/s c= λν 1. (2 points) Which of the following experiment discover nucleus carries positive charge? a. Gold foil b. Millikan oil drop c. Cathode Ray d. None of above 2. (2 points) Calculate the mass (in g) of 2.0 × 10 24 atoms of Hg a. 3.9 × 10 2 g b. 3.2 × 10 2 g c. 1.5 × 10 2 g d. 6.6 × 10 2 g 3. (2 points) Which of the following contains the most number of atoms? a. 1.5 mole of He b. 40 grams of Ar c. 6.02 x 10 23 Ne atoms d. 80g of Ag 4. (2 points) Calculate the frequency in hertz of electromagnetic radiation that has a wavelength of 720.0 nm. (Speed of light = 3.00 X 10 m/s) c= λν ⁸ a. 416.7 s -1 b. 2.16 x 10 8 s -1 c. 2.40 x 10 14 s -1 d. 4.17 × 10¹⁴ s⁻¹ 5. (2 points) The density of helium in a balloon is 1.18 g/L. If a balloon holds 2.93 L of He, how many atoms of He are in the balloon? a. 5.21 × 10²³ atoms c. 1.04 × 10² 4 atoms b. 5.21 × 10² 4 atoms d. 2.08 × 10² 4 atoms 6. (2 points) and contains (a) the same number of neutrons, (b) the same number of protons, (c) the same number of nucleons, (d) the same total number of subatomic particles 7. (6 points) Determine the number of protons, neutrons, electrons and nucleon respectively, in each of the following: a. Al b. I c. N 3- Mass number: Al: 27, I: 127, N: 14 Atomic number: Al: 13, I: 53, N: 7 Proton Neutron Electron Nucleon Al 13 14 13 27 I 53 74 53 127 N 3- 7 7 10 14 Cl 37 17 Ar 36 18

Name: _______________________ 8. (4 points) What is the de Broglie wavelength(in nm) of an electron traveling at 5.46×10 6 m/s? Mass of electron is 9.1 x 10 -31 kg. No work no credit λ = 6.6x10 -34 J.s/(9.1 x 10 -31 x 5.46×10 6 ) = 1.32 x 10 -10 m = 0.132nm 9. In photoelectric effect experiment, the frequency of the photon is 3.30 x 10 15 Hz. Electron escaped from the metal with 1.87 x 10 6 m/s of speed. What is the threshold frequency of the electron? Mass of electron is 9.1x10 - 31 kg, 1ev= 1.6x10 -19 J, 1kg = 1000g, 1m = 10 9 nm, h= 6.6 x 10 -34 Js, Kinetic energy = ½ mv 2 E= BE + KE E = hν = 6.6 x 10 -34 x 3.3 x 10 15 = 2.18 x 10 -18 J KE = ½ x 9.1x10 -31 x (1.87 x 10 6 ) 2 = 1.6 x 10 -18 J BE = E- KE = 2.18 x 10 -18 J - 1.6 x 10 -18 J = 5.78 x 10 -19 J = hν = 6.6 x 10 -34 x ν ν = 8.76 x 10 14 Hz

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Name: ____________ Quiz 2 Makeup Molar Mass = Mass/mole 1 mole = 6.02x10 23 E=hν λ =h/mv h: 6.6x10 -34 Js c= 3.00x 10 8 m/s c= λν 1. (2 points) Which particle would have the shortest de Broglie wavelength traveling with the same velocity? a.He b. Xe c. Electron d. Neutron None of above 2. (2 points) Which of the following contains the least atoms? a. 10g of Mg b. 10g of Ca c. 10g of He d. 10g of Hg 3. (2 points) What is the mass of 8.37 x 10 23 He molecules? a. 5.55g b. 11.1g c. 1.39 g d. 2.78g 4. (2 points) Which of the following experiment proposes the nucleus model? a. Cathode Ray b. Millikan oil drop c. Gold foil d. None of above 5. (2 points) Once upon of a time, there was a handsome Prince who rode a white horse to rescue a Princess from a dragon -dungeon. He rode across plains, mountains, rivers, and deserts in sunny days, cloudy days, snow storm, and rainy days. When he arrived at the dungeon, the rain had just stopped. He saw the bright color of the rainbow was fading on both ends. He was thinking……… The different color was caused by a. The dragon’s warning sign c. Different wavelengths of the light b. Wave amplitude d. Constructive interference 6. The density of helium in a balloon is 1.18 g/L. If a balloon holds 5.86 L of He, how many atoms of He are in the balloon? a. 5.21 × 10²³ atoms b. 1.04 × 10² 4 atoms c. 5.21 × 10² 4 atoms d. 2.08 × 10² 4 atoms 7. (12 points) Determine the number of protons, neutrons, electrons and nucleon respectively, in each of the following: a. O 2- b. Al +3 c. N Mass number: O: 16, Al: 27, N: 14 Atomic number: O: 8, Al: 13, N: 7

8. (4 points) What is the de Broglie wavelength(in nm) of an electron traveling at 3.21×10 4 m/s? Mass of electron is 9.1 x 10 -28 g. No work no credit λ = 6.6x10 -34 J.s/(9.1 x 10 -31 x 3.21×10 4 ) = 2.27 x 10 -8 m = 22.7nm 9. (8 points) In photoelectric effect experiment, electron escaped from the metal with 2.67 x 10 6 m/s of speed. The binding energy of electron is 3.7ev. What is the wavelength of the light? Mass of electron is 9.1x10 -28 g, 1ev= 1.6x10 -19 J c ν 3.00×108 m/s 5.8×1015 s-1 E = hν = BE + KE BE= 3.7 x 1.6x10 -19 = = 5.9×10 -19 J KE = ½ x 9.1x10 -31 kg x (2.67 x 10 6 m/s) 2 = 3.2×10 -18 J E = 3.2×10 -18 J + 5.9×10 -19 J = 3.8×10 -18 J = hν = (6.63×10-34 J s) ∙ ν ν = 5.8×10 15 s -1 Mass of electron = 9.1x10 -28 g = 9.1x10 - 31 kg = λ = = 5.2×10 -8 m