Answer:
A conjugated system can only contain two alkenes: False
B. A cumulated diene is less stable than an isolated diene.
False
Explanation:
A. A conjugated system is more stable than an unconjugated system.: True
Due to resonance a conjugated system is more stable.
B. The s-trans isomer is favored over the s-cis isomer.: True
Due to repulsion in s-cis isomer they are less stable.
C. A conjugated system has multiple resonance structures.
True
This is the reason they are stable.
D. A conjugated system can only contain two alkenes: False
A conjugated system may have may alternate double and triple bonds.
2) A trans alkene releases less heat upon hydrogenation than a cis alkene.
True
Trans alkenes are more stable than cis alkene. Thus heat of hydrogenation of trans alkene is less than cis alkene.
B. A cumulated diene is less stable than an isolated diene.
False
C. Multiple products can always form when treated a conjugated diene with HBr. True
There can be 1,2 or 1,4 addition
D. Conjugated systems arise only between sp2-hybridized atoms.
True
Conjugation allows resonance which is possible in sp2 systems
E. Conjugated double bonds involve unhybridized p-orbitals aligned with each other
True
The double bond is formed as pi bond due to side ways overlapping of unhybridized p orbitals
