Organic Chemistry With Biological Topics 5th Edition By Janice Smith – Test Bank

Chapter 11 Test Bank: Alkynes Key

1. Which of the following molecular formulas is consistent with the formula for a molecule containing one alkyne and no other degrees of unsaturation?
2. I
   B. II
   C. III
   D. IV

6. How many s bonds and p bonds are present in a triple bond?
7. One s bond and one p bond.
   B.One s bond and two p bonds.
   C. Two s bonds and one p bond.
   D. Two s bonds and two p bonds.

7. Which of the following statements about alkynes is not true?
8. Alkynes undergo many addition reactions.
   B.Alkynes are more polarizable than alkenes.
   C. Both p bonds of a C-C triple bond are weaker than a C-C s bond.
   D. The electrons in the p bonds of alkynes are more tightly held than those of alkenes.

15. Which of the following about the physical properties of alkynes is not true?
16. Alkynes have low melting and boiling points.
    B.Melting and boiling points increase as the number of carbons increases.
    C. Alkynes are soluble in organic solvents.
    D. Alkynes are soluble in water.

16. Which of the following explains why 1-pentyne has a slightly higher boiling point than 1-pentene?
17. 1-Pentyne has more carbons than 1-pentene.
    B.1-Pentyne has more carbons per hydrogen than 1-pentene.
    C. 1-Pentyne is linear while 1-pentene is trigonal planar.
    D. The C-C triple bond in 1-pentyne is more polar than the C-C double bond in 1-pentene.

21. Which of the following statements about the reactions of alkynes is not true?
22. Alkynes contain easily broken p bonds.
    B. Alkynes undergo addition reactions.
    C. When alkynes undergo two sequential addition reactions, four new s bonds are formed.
    D. When alkynes undergo two sequential addition reactions, two new s bonds and a p bond are formed.

27. Which of the following bases cannot deprotonate acetylene? You are given the pK_a values of the conjugate acids in parentheses.

1. Only I and II
   B. Only I and III
   C. Only II and III
   D. Only II and IV

30. In the addition of HBr to 1-butyne, the electrophile in the first step of the mechanism is:
31. The Csp-H1s bond of 1-butyne.
    B.The C-C triple bond of 1-butyne.
    C. The H atom in HBr.
    D. The Br ion.

31. In the addition of HBr to 1-butyne, the nucleophile in the first step of the mechanism is:
32. The Csp-H1s bond of 1-butyne.
    B.The C-C triple bond of 1-butyne.
    C. The H atom in HBr.
    D. The Br ion.