Alkynes and Benzene

Which among the following product is formed when ethyne undergoes hydration?

• Formaldehyde

• Formic acid

• Acetaldehyde

• Acetic acid

Select the incorrect statement regarding terminal alkynes.

• 1-propyne is an example of terminal alkynes

• Terminal alkynes are more acidic when compared with alkenes

• Terminal alkynes are not as acidic as alkanes

• These have a replaceable acidic hydrogen atom

1-butyne and 2-butyne can be identified by using which of the following reagents?

• O₂

• Br₂

• NaNH₂

• HCl

In the ozonolysis reaction, acetylene forms

• Formaldehyde

• Glycol

• Formic acid

• None of the above

What would the product of the reaction of 1-butene with bromine be?

• 2-bromobutane

• 1-bromobutane

• 2,3-dibromobutane

• 1,2-dibromobutane

What is the IUPAC name for this compound?

• 1-fluoro-1,1,4,4-tetramethyl-2-butyne

• 2-fluoro-2,5,5-trimethyl-3-pentyne

• 5-fluoro-1,1,5-trimethyl-2-pentyne

• 2-fluoro-2,5-dimethyl-3-hexyne

What are the relationships between double and single bonds?

• Double bonds are longer, and therefore, stronger than single bonds.

• Double bonds are longer, and therefore, weaker than single bonds.

• Double bonds are shorter, and therefore, stronger than single bonds.

• Double bonds are shorter, and therefore, weaker than single bonds.

a) What catalyst is needed for hydrogenation?

b) What is needed for halogenation?

• a) Pt, Pd or Ni

  b) UV light

• a) H⁺

  b) Heat

• a) [O]

  b) Heat

• a) [-O]

  b) H⁺

Resonance in benzene is stabilized due to

• strong covalent bond

• strong pi bond

• delocalization of pi electrons

• delocalization of sigma electrons

What did Kekulé suggest as a structure for benzene?

• A 3D cage of carbons with a complex system of bonds between them, with one hydrogen attached to each carbon

• A ring of six carbon atoms with a stable, delocalised system of s-electrons forming bonds between the carbons and the single hydrogen atom bonded to each carbon

• A long, long chain of carbons and hydrogens with alternating single and double bonds between the carbons

• A ring of six carbons with alternating single and double bonds between the carbons, with one hydrogen atom bonded to each carbon