SCI 3101 Test IV MULTIPLE CHOICE. 1) The sky is blue because air molecules in the sky act as tiny A) mirrors that reflect only blue light. B) prisms. C) sources of white light. D) resonators that scatter blue light. E) none of these 2) The whiteness of clouds is evidence in the clouds for a variety of A) molecules. B) "seeds" upon which condensation of cloud material forms. C) water prisms. D) light intensities. E) particle sizes. 3) Diffraction is a result of A) interference. B) polarization. C) reflection. D) refraction. E) dispersion. 4) Colors seen when gasoline forms a thin film on water are a demonstration of A) reflection. B) interference. C) refraction. D) dispersion. E) polarization. 5) Diffuse reflection occurs when the size of surface irregularities is A) small compared to the wavelength of the light used. B) large compared to the wavelength of the light used. 6) A mirage is a result of atmospheric A) scattering. B) refraction. C) aberrations. D) dispersion. E) reflection. 7) Light refracts when traveling from air into glass because light A) intensity is greater in air than in glass. B) frequency is greater in glass than in air. C) frequency is greater in air than in glass. D) intensity is greater in glass than in air. E) travels slower in glass than in air. 8) Different colors are dispersed by a prism because different colors in the prism have different A) speeds. B) energies. C) directions. D) frequencies. E) none of these 9) Your image in a plane mirror is A) virtual. B) real. C) both of these D) neither of these 10) What makes an element distinct? A) the number of electrons B) the number of protons C) the number of neutrons D) the total mass of all the particles 11) Which of the following are electrically neutral? A) electron B) proton C) neutron D) none of these 12) Which has the greatest number of protons in its nucleus? A) silver (Ag) B) mercury (Hg) C) gold (Au) D) lead (Pb) 13) If two protons are removed from an oxygen nucleus, the result is A) carbon (C). B) nitrogen (N). C) helium (He). D) neon (Ne).
14) If an atom has 43 electrons, 56 neutrons, and 43 protons, what is its approximate atomic mass? What is the name of this element? A) Atomic mass 142 amu; Einsteinium (Es) B) Atomic mass, 99 amu; Radon (Ra) C) Atomic mass, 137 amu; Barium (Ba) D) Atomic mass, 99 amu; Technetium (Tc) 15) Why are the atomic masses listed in the periodic table not whole numbers? A) The atomic masses are average atomic masses. B) Scientists have yet to make the precise measurements. C) That would be too much of a coincidence. D) Today's instruments are able to measure the atomic masses to many decimal places. 16) Suppose that a certain atom possesses only four distinct energy levels. Assuming that all transitions between levels are possible, how many spectral lines will this atom exhibit? A) six B) three C) four D) unlimited 17) Which radiation has no electric charge associated with it? A) beta rays B) alpha rays C) gamma rays D) none of these 18) Different isotopes of an element have different numbers of A) protons. B) photons. C) neutrons. D) neutrinos. 19) The half-life of an isotope is one day. At the end of two days the amount that remains is A) none. B) one-half. C) one-quarter. D) one-eighth. 20) When an element undergoes nuclear transmutation, the result is a completely different A) ion of the same element. B) isotope of the same element. C) element. 21) In both fission and fusion, mass A) is changed to the form of kinetic energy. B) remains the same. C) is created from energy. 22) A solid is not considered fluid because A) its atoms or molecules are under too much pressure. B) of the heavy nature of its atoms or molecules. C) of the fixed arrangement of its atoms or molecules. D) its atoms or molecules are bound as close together as possible.
23) How is a physical change different from a chemical change? A) The chemical identity of a substance is not altered during a physical change. B) A physical change involves changes in chemical properties. C) The chemical identity of a substance is altered during a physical change. D) The physical properties of a substance are not altered during a chemical change. 24) Is the following transformation representative of a physical change or a chemical change? A) physical change because a new material has been formed B) chemical change because of the formation of elements C) physical change because of a change in phase D) chemical change because the atoms are connected differently 25) To say a chemical equation is balanced means the A) coefficients on both sides of the reaction add up to the same number. B) number of times each element appears as a reactant is equal to the number of times it appears as a product. C) subscripts on both sides of the reaction add up to the same number. D) number of molecules of reactants and products are equal.
Problems (5 points each) 1) If an atom has 15 electrons, 17 neutrons, and 15 protons, what is its approximate atomic mass? What is the name of this element? Atomic Number: 15 Mass Number or Atomic Mass: 32 amu Element: Phosphorus, P 2) A certain radioactive substance has a half-life of one hour. If you start with 1 gram of material at 12:00 Noon, how much will be left at 3:00 PM? 1g 1/2g 1/4g 1/8g After 3 half-lifes, 1/8g remains. 3) Complete the following nuclear reactions: 88 Ra 226 0 1 e Ra Ac 226 226 0 88 89 1 e 238 4 92 U 2He 4 92 U 2He 238 234 90 Th 4. Name the following substances: NaCl Li 2 O Sr 3 P 2 Sodium Chloride Lithium Oxide Strontium Phosphide
5. Balance the following chemical reactions: CH 4 (g) O 2 (g) CO 2 (g) H 2 O(l) 1_ CH 4 (g) 2_ O 2 (g) 1_ CO 2 (g) 2_ H 2 O(l) Cl 2 (g) KBr(s) Br 2 (l) KCl(s) 1_ Cl 2 (g) 2_ KBr(s) 1_Br 2 (l) 2_ KCl(s)