1989 AP - U.S. National Chemistry Olympiad: 1989 National...

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U.S. National Chemistry Olympiad: 1989 National Test Go to the answers 1. Gallium reacts with element Y to form a compound with the formula GaY. If barium were to combine with element Y, the formula of the product would most likely be (A) BaY (B) Ba 2 Y (C) Ba 2 Y 3 (D) Ba 3 Y 2 2. The number of significant figures one can assume in the atomic weight of 12 C is (A) 2 (B) 3 (C) 4 (D) unlimited 3. A compound X 2 O 3 contains 31.58% oxygen by weight. The atomic weight of X is (A) 34.66 g/mol. (B) 45.01 g/mol. (C) 52.00 g/mol. (D) 104.0 g/mol. 4. The emission spectrum of the hydrogen atom (A) is caused by the removal (ionization) of the electron. (B) is continuous because the electron can emit any frequency of light during a transition. (C) is caused by the absorption of light at characteristic frequencies the electron to be excited into higher energy levels. (D) is a result of the excited electron undergoing transitions to lower energy levels and emitting photons of light at specific frequencies. 5. Cathode rays are (A) a beam of positively charged particles. (B) nuclei of helium atoms. (C) fast-moving neutrons. (D) streams of electrons. 6. Which atom has the correct ground state electron configuration?
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(A) Cl: [Ne]3s 1 3p 6 (B) Mo: [Kr]5s 1 4d 5 (C) Cu: [Ar]4s 2 3d 8 (D) As: [Ar]4s 2 4d 10 4p 3 7. The correct number of unpaired electrons in the ground state of a neutral cobalt atom is: (A) 1 (B) 2 (C) 3 (D) 4 8. Which electron configuration describes a neutral atom in an excited state? (A) [Xe] 6s<sup2< sup=""> 4f 14 5d 10 6p 3 (B) [He] 2s 1 (C) [Ne] 3s 1 3p 1 (D) [Ar] 4s 1 3d 5 </sup2<> 9. The first ionization potential for S is lower than the first ionization potential for P because (A) Hund's rule is violated. (B) ionization potentials decrease across a representative period. (C) half-filled and filled sets of orbitals are more stable than configurations of one more or fewer electrons. (D) The statement above is false. The first ionization potential for S is higher than that for P. 10. Which set of quantum numbers describe the most easily-removed electron from a neutral iron atom? (A) n = 4, l = 0, m = 0, s = -1/2 (B) n = 3, l = 2, m = 0, s = +1/2 (C) n = 3, l = 2, m = -1, s = -1/2 (D) n = 1, l = 0, m = 0, s = -1/2 11. The molecular ion XF 2 ¯ has three pairs of non bonding electrons around the central atom. The bond angle F-X-F will be closest to (A) 180°. (B) 120°. (C) 109°. (D) 90°. 12. Which species has a pyramidal structure? (A) ClO 2
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(B) ClO 2 ¯ (C) ClO 3 ¯ (D) ClO 4 ¯ 13. Which molecule is polar? (A) CO 2 (B) SF 6 (C) BCl 3 (D) SF 4 14. Which of the following sets have correctly matched each molecule or ion and its geometry? Tetrahedral
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1989 AP - U.S. National Chemistry Olympiad: 1989 National...

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