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Practice Exam 2 - Quiz CH301 1351112009 Practice Exam 2...

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Unformatted text preview: Quiz: CH301 1351112009 Practice Exam 2 Page 1 of 11 CH301 Fall 2009 Practice Exam 2 Your response has been submitted successfuliy. —'DJ 1. Which of the following is poiar? H / \ A. SF6 W B910 ‘ ' _ 4 . 0, SF4 _- ‘ ‘(K .\_ M m" D.ASF6_- . v i «1: fl I: fitm- _‘ .;_:.E' X654 , _‘ 7. 1 A / . ,, P ‘ . Points Earned: 0/1 Correct Answer: C Your Response: " 199292 Points Ea mieféil:§-0/ 11%} f - Correct Answ YWPRgsponsé 3, Wh'i'Chliouf the folfowing hasbondangies sfi-ig'h‘l’ltly less than 109°? A. NH4+ 3- 004‘ C. 92- http://angei.bfi?vpub.conflseciion/content/defauit.asp?WCImpgDisp1ay%5FQuizSaWCEms... 25/ I 0/2009 Quiz: CH30] Fall 2009 Practice Exam 2 Page 2 of 11 Br03_ 3... D. p04 E. 8H4“ Q. Points Earned: 0/1 Correct Answer: C Your Response: 4. With which of the haiogens wili carbon form the least polar bond? A. F 3. Cl \/ C. Br D.I E. Halogens form non—polar bonds with carbon Points Earned: 0/1 Correct Answer: D Your Response: 3. SiH4 exhibits a single spectroscopic peak associated with the Si—H bond. Why i \ is surprising? he atomic orbitals from which SIH4 is formed are not degenerate B. There should be pi bonds formed for n=3 row atoms. .. Hybridization of Sii—iciL is hypervalent. " Sil—l4 should have a spectrum like CH4 which exhibits multiple peaks. Points Earned: 0/ 1 Correct Answer: A Your Response: http: Hangel bprub conflsection/conten’t/default. asp’PWCI"p0D15p1ay%5F Qu:z&WCE— . 25/10/2009 Quiz: CH301 Fall 2009 Practice Exam 2 Page 3 of 11 Correct Answer: 8 Your Response: 7.. What is the shape of the molecule AX4E2? i A. octahedrai B. tetrahedral Q C. seesaw I 9. square planar E. square pyramidal Points Earned: 0/1 Correct Answer: D Your Response: 8. How many sigma and pi bonds are there in 0 ”g @One sigma bond and one pi bond. .1 B. One sigma bond. ‘ 0 : r C. Two pi bonds. i D. Three sigma bonds. , i The correct answer is A. An oxygen moiecuie has a double bond which is composed of one sigma and one pi bond. Points Earned: D/Zi Correct Answer: A Your Response: ,.9...Accorciing to the MO theory, when a nitrogen molec ‘ u .-s an electron: I®A more stable positive ion is formed. B. A less stable positive ion is formed. C. A more stable negative ion is formed. D. None of the above. _ The correct answer is B. A moiecuie's stability increases as bond order increases. According to the building—up principie, the bond orders of NZ and N2+ are 3 and 2.5 respectiveiy. Points Earned: 0/1 Correct Answer: B Your Response: are? hepWangel.bprub.coedsection/content/defauit.asp?WCI--~pgDisplay%5FQuiz&WCE:s. .. 25/10/2009 Quiz: CHEOE. Fall 2009 Practice Exam 2 Page 4 of 11 1e. Which of the following is diamagnetic? 2_ . A. 02 B. 82 C. 02"“ D. 02+ Points Earned: 0/1 Correct Answer: A Your Response: 11. Which of the folloWing has the longest bond? A. N2 Points Earned: 0/1 Correct Answer: E _' Your Response: 12. Draw the C2F4 molecule. The atomic orbits that contribute to the sigma bonds formed between carbon and fluorine atoms are: A. 5:92 for C and 53:32 for F B. 5:33 for C and‘spZ for F C. so for C and sp3 for F D. 592 for C and 5133 for F E. sp3 for C and so for F . Points Earned: 0/1 Correct Answer: D Your Response: 13. In drawing the molecular orbital diagrams drawn for the diatoms below, which exhibits unpaired electrons in the pi molecular orbitals formed from 2p atomic orbits? http://angel.bprub.com/sectionfcontent/defauIt.asp?WCI==pgDisplay%5FQuiZ&WCEmS. .. 25/10/2009 Quiz: CH301 Fall 2009 Practice Exam 2 Page 5 0f 11 A. Li2 B. BeZ C. 82 D. C2 E. N2 Points Earned: 0/1 Correct Answer: C Your Response: e -- nouncis exhibits three delocaiized pi bonds? 14.. WHich of the followim A. benzene B. nitrate ion C. carbonate ion D. sulfate ion E. formic acid Points Earned: 0/1 Correct Answer: A Your Response: 15. Determine the bond orders and use them to predict which of the following , species has the stronger bond: _ + \/ A e + 3- Be-2 The correct answer is A. A molecule's stability increases as bond order increases. According to the building-up principle, the bond orders of {3612+ and Ff are 0.5 and 1.5 respectively. Points Earned: 0/1 Correct Answer: A Your Response: 6. If 250.0 mi. of a gas at STP weighs 2.00 9, what is the molar mass of the gas? A- 28.0 giiiimoi”1 3‘ 179 gljmol"l C- 8.00 gamer”1 A \/ \ http://ange1.bprub.com/section/content/default.asp?WCI=pgDisplay%5FQuiz&WCE=s... 25/ E 0/2009 Quiz: CH301 Fall 2009 Practice Exam 2 Page 6 of 11 D- 56.0 g moi—1 5- 44.8 meol‘l' Points Earned: 0/1 Correct Answer: B Your Response: 17. Consider the following reaction: 4K02(s) + 2C02(g),-+ 2K2C03(s) + 302(g) How many moles of KO2 are needed to react with 75.0 L of carbon dioxide at —25°C and 215 kPa? A. 3.91 B. 7.82 C. 31.3 D. 23.5 E. 15.6 Points Earned: 0/1 _ Correct Answer: E ' Your Response: 18. The following experiment was carried out using a newly synthesized chlorofluorocerbon. Exactly 50 ml. of the gas effused through a porous barrier in 157 s. The same volume of argon effused in 76 5 under the same conditions. Which compound is the chlorofluorocarbon? A.CZCI4F2 ‘B.C2CW5- u,. {/1 C.C2C|2F4~- ‘ ’ ' o.c2ch ~ ‘ E. c203r3 Points Earned: 0/1 Correct Answer: C Your Response: 19. What is the temperature in Kelvin, needed to double the volume of an ideal gas initially at 25°C if the pressure were to decrease by 90.0%? Give your answer to one decimal place. Q http://angel.bprub.com/section/content/default.asp?WCI=pgDisplay%5FQuiz&WCE=s... 25/10/2009 Quiz: CH301 Fall 2009 Practice Exam 2 Page 7 of 11 A. 59.6 K B. 298 K C. 5 K D. 29.8 K The correct answer is A. .. Since n is constant we use the combined gas Law with n1 = r72: P2V2 T1 T2 We rearrange the above equation to find T2: P2V2T1 Plvl Since V2 = 2V1 and P2 w 0.1OPl we obtain: ‘ (0.103.9(21/1)?“1 2 2W Plvl T2 :- 020 T1 74 O.20(298 K) :- 59.6 K Points Earned: 0/1 Correct Answer: A ‘ Your Response: 20. Ideal gases and real gases behave most similariy un which of the foiiowing B. Low temperatures and high pressures. C. High pressures and low moiar masses. D. Hightemperatures and high pressures. E. High temperatures and 30w pressures. _ c editions? /‘ . Low temperatures and 30w pressures. Points Earned: 0/ 1 Correct Answer: E Your Response: 21. Which of the foiiowing' molecuies wiii exhibit the greatest non~ideality in the gas phase clue to attractive forces? A. SF6 B. PFS c. 03 $0 ZED http://angei.bprub.oom/section/content/default.asp?WCI=pgDispiay%5FQuizSLWCEms... 25/10/2009 Quiz: CH301 Fall 2009 Practice Points Earned: 0/1 .4 a PageSofll D. CHBOH E. 802 Correct Answer: if) Your Response: 22. Which of the following scientists first explained why it is that when Dr. Laude sits on a balloon the volume decreases? QXQEQROW hate, A. Charles /T (Wheres/dd], Uozr B. Guy Lussac ‘ . [30L J, C. Boyle ““ -i>l‘@5m(l/ VUZDWYW/J/ 01/ ‘ y D. Avagadro an vim-6+6. mew/3; WW \f/ Mat/WW E. Rydberg Points Earned: 0/1 Correct Answer: 'C Your Response: 23. Ethanol ,CHBCHon, has a much higher boiling point than dimethyi ether (7 CHBOCHB, 785°C and ~23.6°C respectively. Q _ ‘ What might be the reasdn for this? W / /\0 W . ”6539} A. The molar mass of ethanol is higher. % ‘30 Q\ B. Ethanol is a polar molecule while dimethyl ether is a nonpoiar molecule. 5- Ethanol is an ionic compound (CH3CHZO~ and H+) whereas dimethyl ether is a molecular compound. 3:). Ethanol molecules form hydrogen bonds, while dimethyl ether molecules cannot form hydrogen bonds among themselves. _ . ‘ . The correct answer is D. ,, In ethanol the H atom is bonded directly to an O atom whereas in dimethyl ether the H atom is bonded to a C atom. Therefore, Ethanol moiecules form hydrogen bonds, while dimethyl ether molecuies can not form hydrogen bonds among themselves. Since hydrogen bonds are the strongest type of intermolecular interactions and stronger intermolecular interactions result in higher boiling points, ethanol has a higher boiling point than dimethyi ether. Points Earned: 0/1 Correct Answer: D Your Response: 24. Which of the following can form intermolecular hydrogen bonds? http:”angel.bprub.corrusectionfcontent/default.asp?WCIEpgDisplay%5FQuiz&WCEr—"s. .. 25/10/2009 Quiz: CH301 Fall 2009 Practice Exam 2 . Page 9 of 11 {l 3* A.PH3 \ 3. HI XE“)? 4‘ C.CH3CH2CH2CH2CH3 W ~- D.HCOOH a. CH3CHZOCH2CH3 Points Earned: 0/1 Correct Answer: D Your Response: 25‘. Which of the following has the lowest boiling point? Points Earned: 0/1 Correct Answer: C Your Response: 7:26. What are all the intermolecular forces that are responsible for the existence of " ice? Wk (\ A. dipole-dipole and London forces %0 % C \635 «MS 0 / B. London forces §~\§ _ gfl‘ béfig C. emote-dipole, London forces,_ and hydrogen bonding ”RN “ ii 5\ D. dipole-dipole and ion—ion ' “\ka 0““ wsw ‘06 ® hydrogenbonding and dipoie~dipole I ‘ key“? N“ 9r 5R Points Earned: 0/1 Correct Answer: C Your Response: 27. A structure of the liquid crystal SCB is shown below. @ How can we modify the molecule to obtaqin a molecule with a higher melting point? http://angel.bprub.comfsection/content/default.asp?WCIngDisplay%5FQuiz&WCE=S... 25/10/2009 Quiz: CH301 Fall 2009 Practice Exam 2 Page 10 of 11 A. Repiace the CN group with OH group. /7 B. Repiace the CN group with CH3 group. ( (2. Replace the CN group with CF3 group. D. Repiace one H atom on the ring with methyl (CH3) group. The correct answer is A. The forces existing between the CN groups in two of the given moiecuies are dipole—dipole forces. Replacing the CN group with an OH group enables hydrogen bonding between these groups. Hydrogen bonds are stronger than dipole—dipole forces, therefore the new molecule will have a higher meiting point. . Points Earned: 0/1 Correct Answer: A Your Response: 28. Which of the foliowing statements is true? A. Butane, C4H10, has a higher boiiing point than acetone, CH3COCH3. B. Pentane, CsHizr has a lower boiling point than 2,2—dimethylpropane, C5H12' 'c. CHF3 has a higher boiling point than cs4. _ q _ 0L §VK§ ’ t "r o. CH 4 has a higher boiiing point than cc14. E. HI has a lower boiling point than HBr. Points Earned: 0/1 Correct Answer: C Your Response: A. ionic . 3. network covalent C. moiecular I D. metallic Points Earned: O/l Correct Answer: 13 Your Response: 3%. When water boils, which of the foliowing is true: A. Water vapor condenses at the water surface ; {\ \g httpWangel.bprub.com/section/contenfldefaultesp?WCIflpgDisplay%5FQuiz&WCE=s... 25/10/2009 Quiz: CHBOl Fall 2009 Practice Exam 2 Page 11 of 11 B Water vapor escapes because the vapor pressure exceeds the atmospheric pressure .- C. Water vapor escapes because the atmospheric pressure exceeds the vapor pressure D. pockets of atmOSpheric gases achieve escape veiocities exceeding Maxweii velocities Points Earned: 0/1 Correct Answer: 8 Your Response: http: Hangel bprub. com/section/content/defauit. asp?WCI'pgDisp1e§/%SFQuiz&WCE=s.. . 25/10/2009 ...
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