20A Molecular Structures - Assignment Answer Key

Anglo-Chinese School (Barker Road) A Methodist Institution Founded in 1886 CHEMISTRY DEPARTMENT OF SCIENCE Name: ANSWERS ( ) Class: SEC 4 OC: MOLECULAR STRUCTURES – ASSIGNMENT ALEX LEE/2010 PAGE 1 OF 5 PURE/COMBINED/N-LEVEL Multiple-Choice Questions [20 Marks] TOTAL SCORE / 30 Write in your selected answer for the multiple-choice questions in the boxes provided. 1 2 3 4 5 6 7 8 9 10 C C A B C B C C B C 11 12 13 14 15 16 17 18 19 20 C B B C A A C A A C 1. All members of an homologous series A contain the same number of bonds. B contain the same number of carbon atoms. C share a general formula. D share the same melting and boiling points. 2. Which of the following statements about an homologous series is false? A Members of a homologous series contain a different number of hydrogen atoms. B Members of a homologous series have different melting and boiling points. C Members of a homologous series share the same empirical formula. D Members of a homologous series undergo similar chemical reactions. 3. Down a homologous series, the boiling points of each successive member increases because A the intermolecular forces between the molecules increases. B the number of hydrogen atoms increases. C there are a larger number of bonds to be broken. D there covalent bonds are get increasingly stronger. 4. Which of the following is not a trend across a homologous series, in order of increasing number of carbon atoms? A Increasing density. C Increasing mass. B Increasing flammability. D Increasing viscosity. 5. Which of the following is a possible general formula for carboxylic acids? A CnH2n+1COH B CnH2nCO2H C CnH2nO2 D CnHn+1CO2H

ALEX LEE/2010 PAGE 2 OF 5 6. What is the molecular formula for propanoic acid and butanol? propanoic acid butanol A C2H5COOH C3H7OH B C2H5COOH C4H9OH C C3H7COOH C3H8O D C3H7COOH C4H10O 7. Which of the following correctly states the molecular formula, empirical formula and simplified structural formula of propene? molecular formula empirical formula structural formula A CH2 C3H6 CH2CHCH3 B CH2CHCH3 CH2 C3H6 C C3H6 CH2 CH2CHCH3 D C3H6 CH2CHCH3 CH2 8. Cycloalkanes are compounds with a ‘ring’ carbon chain. Two examples of cycloalkanes are cyclopentane and cyclohexane: cyclopentane cyclohexane Which of the following correctly shows the general formula for alkanes, alkenes and cycloalkanes? alkanes alkenes cycloalkanes A CnH2n CnH2n CnH2n+2 B CnH2n CnH2n+2 CnH2n C CnH2n+2 CnH2n CnH2n D CnH2n+2 CnH2n CnH2n+2 9. Which of the following statements about the alkene homologous series is true? A All members are gaseous at room temperature. B All members have the same empirical formula. C All members have the same molecular mass. D All members have the same structural formula. 10. Which of the following statements about the alcohol homologous series is true? A All members are hydrocarbons. B All members ar