UV Spectroscopy

If two double bonds of a cyclic diene are present in the same ring, it is called ……. diene.

• Homoannular

• Heteroannular

• Homocylic

• Heterocyclic

Trans- stilbene absorbs at longer wavelength than cis- stilbene because …..

• steric hinderance in cis- stilbene

• Planarity is disturbed in cis- stilbene

• Mobility of electron is more in trans- stilbene than in cis- stilbene

• All the above

Which one of the following has maximum value of lambda max

• Acetone

• Ethyl methyl ketone

• Methyl vinyl ketone

• Acetaldehyde

UV spectroscopy is not useful for distinguishing between ………

• Conjugated dienes

• Carbonyl compounds and enones

• Functional isomers

• Geometrical isomers ( Cis-Trans Isomers)

UV spectroscopy provides information about presence of ……..

• Multiple bond

• Extent of conjugation

• Aromatic rings

• All of the above

If a double bond is exocyclic to two rings,  $\lambda$ max increases by ………. nm

• 5

• 10

• 20

• 30

UV Spectroscopy is used to distinguish between cis and trans isomers

• True

• False

A compound having  $\lambda$ max 215nm indicates....

• Presence of conjugation

• Presence of carbonyl group

• Aromatic Compound

• Auxochrome

• All of the above

Which of the following compound absorb at higher  $\lambda$     max....

• Cis Azobenzene

• Trans Azobenzene 

• Both Cis Azobenzene and Trans Azobenzene 

• None of these

Basic  $\lambda$  max value or parent value for heteroannular diene is

• 253 nm

• 256 nm

• 213 nm

• 215 nm