Solution: Indicate whether the statement is true or false.   A. Heterocycles can “choose” to remain unconjugated if donating a lone pair into the ring will mean the ring has 4n π-electrons.  B. Fully conjugated rings are always more stable than incompletely conjugated rings.  C. If a molecule absorbs a certain wavelength of light, it will appear to be that color to an observer. D. In arrow-pushing mechanisms, the arrows should be drawn originating from the electrophile and terminating at the nucleophile.  E. A cyclic compound that has full conjugation interrupted by one sp3-hybridized carbon will become more acidic if an extra lone pair will result in 4n+2 π-electrons. F. If a molecule releases light, an electron is excited from a bonding orbital to a nonbonding orbital.  G. When two atoms bond, they store energy; when a bond breaks, it releases energy. H. Friedel-Crafts alkylation can be used to add an alkyl group to the para position of aniline.  I. Halides are electron-donating groups and o,p directors. This makes them mild activators toward EAS. J. Benzene is nucleophilic enough for a haloacid to react with it without a catalyst.  K. Diels-Alder reactions can also occur with electron-donating groups on the dienophile and electron-withdrawing groups on the diene.   

Problem

Indicate whether the statement is true or false.

 

A. Heterocycles can “choose” to remain unconjugated if donating a lone pair into the ring will mean the ring has 4n π-electrons. 

B. Fully conjugated rings are always more stable than incompletely conjugated rings. 

C. If a molecule absorbs a certain wavelength of light, it will appear to be that color to an observer.

D. In arrow-pushing mechanisms, the arrows should be drawn originating from the electrophile and terminating at the nucleophile. 

E. A cyclic compound that has full conjugation interrupted by one sp3-hybridized carbon will become more acidic if an extra lone pair will result in 4n+2 π-electrons.

F. If a molecule releases light, an electron is excited from a bonding orbital to a nonbonding orbital. 

G. When two atoms bond, they store energy; when a bond breaks, it releases energy.

H. Friedel-Crafts alkylation can be used to add an alkyl group to the para position of aniline. 

I. Halides are electron-donating groups and o,p directors. This makes them mild activators toward EAS.

J. Benzene is nucleophilic enough for a haloacid to react with it without a catalyst. 

K. Diels-Alder reactions can also occur with electron-donating groups on the dienophile and electron-withdrawing groups on the diene.