Exam 5 Multiple Choice

Question 1

Rank the following compounds from highest wavenumber to lowest wavenumber for their c=o absorption band:

Answer 1

II, III, I

Question 2

Rank the following compounds in order of increasing (from lowest to highest) maximum wavelength:

Answer 2

iii, i, ii, iv

Question 3

Which of the following mass spectra indicate the presence of a halogen?

Answer 3

Peaks 41, 55, 83, 162, 164

Question 4

Which ine of these electrons in a molecule would be easiest to lose by electron impact ionization?

Answer 4

A non-bonding electron

Question 5

Shich compound corresponds tot he IR spectrum shown below?

Answer 5

CH3CH2CH2COOH

Question 6

In the mass spectrum of 2-methylpentane (shown below) a peak at m/z = 43 is most probably due to which fragment?

Answer 6

CH3C+HCH3

Question 7

Which one of these qualitative determinations can not be based on UV-Vis spectroscopy?

Answer 7

Melting point temp for DNA

Question 8

For the section of a mass spectrum shown below the m/z = 41 & 43 amu do not represent isotopic peaks that differ by 2 amu because:

Answer 8

All of A B & C

Question 9

Which one of these compounds will show only 1 C-O absorption in its IR spectrum?

Answer 9

CH3CH2OCH2CH2CH3

Question 10

Ultraviolet spectroscopy provides info about:

Answer 10

Conjugated double bonds

Question 11

A bond that is stiffer is:

Answer 11

Stronger

Question 12

Why is a positively charged oxygen atom less stable than a positively charged nitrogen atom?

Answer 12

Oxygen is more electronegative than nitrogen

Question 13

Which of the following ketones is conjugated to a C=C bond?

Answer 13

CH3COCH=CH2

Question 14

Which would you expect to have the highest C=O wavelength?

Answer 14

H3CC(O)OCH3

Question 15

In the resonance structures of the amide, which is the most important resonance contributor?

Answer 15

The structure with c=o