Chem 1A Final KEY B - F inal Exam Form B, Blue Version Dec....

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Final Exam Form B, Blue Version Dec. 12, 2008 1. (5 pt.) Consider the isotope Br-80: a) It will be stable because the atomic weight of bromine is 79.9, very close to 80 b) It will be stable because it has even atomic mass number c) It will be unstable because it has even number of protons and even number of neutrons d) It will be unstable because it has odd number of protons and odd number of neutrons CORRECT e) Can’t determine 2. (5 pt.) Which of the following is true? a) O-18 and F-19 have the same number of neutrons b) C-14 and N-14 are isotopes of each other c) 18 8 O 2- has the same number of electrons as Ne-20 d) 32 16 S and 32 16 S 2- are isotopes of each other e) (a) and (c) are both true CORRECT 3. (5 pt.) Which of the following compounds does not have the correct chemical formula or does not have the correct name? a) Mg 3 N 2 magnesium nitride b) N 2 O nitrogen dioxide CORRECT RESPONSE (INCORRECT NAME) c) HF hydrogen fluoride d) FePO 4 iron (III) phosphate e) Li 2 O lithium oxide 4. (5 pt.) The element europium exists in nature as two isotopes: Eu-151 has a mass of 150.9196 amu, and Eu-153 has a mass of 152.9209 amu. The average atomic mass of Eu is 151.96 amu. Calculate the relative abundance of Eu-151. a) 48.0% CORRECT b) 52.0% c) 50.0% d) 49.7% e) 50.3 % 1
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5. (5 pt.) When strontium (Sr) forms compounds, what electronic change would you expect? a) Gains one electron b) Loses one electron c) Gains two electrons d) Loses two electrons CORRECT e) Will share electrons in covalent bond 2
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Final Exam Form B, Blue Version Dec. 12, 2008 6. (5 pt.) A metal oxide contains 83.0% metal by mass. Determine the identity of the metal. a) Na b) Ca c) K CORRECT d) Rb e) Sr 7. (5 pt.) AgNO 3 and KBr are mixed in an aqueous solution. For the resulting mixture, which of the following statements is true? a) The precipitate KNO 3 is formed b) No precipitate is formed c) AgNO 3 is not soluble d) Silver metal is plated out e) The precipitate AgBr is produced CORRECT 8. (5 pt.) How many atoms of nitrogen are present in 6.55 g of calcium nitrate? a) 8.26x10 22 b) 3.99x10 -2 c) 2.40x10 22 d) 7.99x10 -2 e) 4.81x10 22 CORRECT 9. (5 pt.) An element’s most stable ion forms an ionic compound with bromine, having the formula XBr 2 . If the ion of element X has a mass number of 230 and has 86 electrons, how many neutrons does it contain? a) 146 b) 144 c) 142 CORRECT d) 140 e) Can’t determine 10. (5 pt.) Balance the following equation using the lowest integer coefficients. 3
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Cr(s) + S 8 (s) Cr 2 S 3 (s) What is the coefficient for sulfur? a) 2 b) 8 c) 3 CORRECT d) 1 e) 16 4
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Final Exam Form B, Blue Version Dec. 12, 2008 11. (5 pt.) Mercury and bromine will react with each other to produce mercury (II) bromide: Hg ( l ) + Br 2 ( l ) HgBr 2 (s) What mass of HgBr 2 is produced from the reaction of 9.51 g Hg and 10.4 g Br 2 ? a)
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Chem 1A Final KEY B - F inal Exam Form B, Blue Version Dec....

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