1987AP - U.S. National Chemistry Olympiad: 1987 National...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
U.S. National Chemistry Olympiad: 1987 National Test Go to answers 1. Assume, as Dalton did, that the atomic weight of oxygen is 7. A sample of 11 g of a uranium oxide contains 10 grams of U. Which of the following is compatible with this data? (A) Uranium oxide is UO and the atomic weight of U is 70. (B) Uranium oxide is U 3 O 8 , and the atomic weight of U is 70. (C) Uranium oxide is UO 2 and the atomic weight of U is 240. (D) Uranium oxide is U 2 O 3 and the atomic weight of U is 240. 2. The mass of a 6-C-12 atom is 19.92679 x 10¯ 24 g and that of a 2-He-4 atom is 6.64658 x 10¯ 24 g. If the international atomic weight scale had defined the mass of a 2-He-4 atom as exactly 4.0, what would be the atomic weight of Li which is 6.941 on the present scale? (A) 6.361 (C) 6.936 (B) 6.941 (D) 6.946 3. Separation of the isotopes of uranium requires a physical method rather than a chemical method because (A) it is too dangerous to mix other chemicals with uranium. (B) the isotopes are chemically the same element. (C) the isotopes differ in number of neutrons. (D) natural uranium contains only 0.7% U-235. 4. The symbol of the element whose nucleus contains 27 neutrons and 22 protons is 5. Analysis of a quantity of it compound shows that it contains 0.110 mol of C, 0.055 mol of N, and 0.165 mol of 0. Its molecular weight is about 270. How many atoms of carbon are there in
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
the empirical formula for the compound and how many in the molecular formula? (A) Empirical - 1. molecular - 3 (B) Empirical - 2, molecular - 2 (C) Empirical - 2. molecular - 6 (D) Empirical - 3, molecular - 2 6. A phenomenon that suggests that light is emitted in packets called quanta is (A) Hess's Law. (B) diffraction of light. (C) blackbody radiation. (D) electron diffraction. 7. The observation that electrons can be diffracted is evidence that electrons (A) have particulate properties. (B) have wave properties. (C) are emitted by atoms. (D) are absorbed by.ions. 8. An electron can move from one orbital of a hydrogen atom to another. In which movement will the photon of highest energy be emitted? (A) 2p ---> 1s (B) 1s ---> 2p (C) 3s ---> 2s (D) 2s ---> 3s 9. The energy in joules of a photon of radiation of wavelength 1.23 x 10¯ 5 m is (A) (6.63 x 10¯ 34 )(3.00 x 10 8 ) / (1.23 x 10¯ 5 ) (B) (6.63 x 10¯ 34 )(1.23 x 10¯ 5 ) (C) (3.00 x 10 8 ) / (1.23 x 10¯ 5 ) (D) (1.23 x 10¯ 5 ) / (6.63 x 10¯ 34 ) 10. Which has the greatest ionization energy? (A) He (B) Ne (C) Ar (D) Cl¯ 11. Which is the smallest? (A) K
Background image of page 2
(B) K + (C) Ca (D) Ca 2+ 12. Which bond would be least polar? (A) H-F (B) B-F (C) Cl-F (D) Ca-F 13. Which end of the bonds Si-Cl. At-Br, and Hg-P are positively charged? (A) Si, At, P
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 17

1987AP - U.S. National Chemistry Olympiad: 1987 National...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online