Question 1

Which of the following molecules is polar, and in which direction does the overall dipole moment point?

A) Benzene
B) 1,2-dichlorobenzene
C) NO$$_2^-
D) $$HCN

Accepted Answer

D) HCN is polar, with the dipole moment pointing from H to N.

Question 2

What is the hybridization and electron geometry of the nitrogen atom in the aniline molecule (C$$_6H$_5NH$_2$$)?

Accepted Answer

sp$$^2$$ hybridization, trigonal planar geometry

Question 3

Which of the following is the most stable chair conformation for bromocyclohexane?

Accepted Answer

Bromine in the equatorial position

Question 4

Provide the IUPAC name for the following structure:

A) (Structure: tert-butylcyclopropane)

Accepted Answer

1-tert-butylcyclopropane

Question 5

When viewed down the C$$_1$$–C$$_2$$ bond, which Newman projection of 1,1-dibromopropane is the most stable?

Accepted Answer

Staggered conformation with Br atoms anti to each other

Question 6

Which of the following pairs are constitutional isomers?

Accepted Answer

Compounds with different connectivity but same molecular formula

Question 7

How many secondary carbon atoms are present in the following molecule?

(Structure: 2,3-dimethylhexane)

Accepted Answer

5

Question 8

Of the indicated bonds in the following molecule, which will be the shortest and why?

A) C=O
B) C–N
C) C–C
D) C=C

Accepted Answer

A) C=O, because double bonds are shorter than single bonds and the C=O bond has partial ionic character

Question 9

Draw all reasonable resonance structures for the following molecule: para-chloroaniline. Which structure contributes most to the resonance hybrid and why?

Accepted Answer

The structure with the lone pair on nitrogen delocalized into the ring, because it allows for maximum conjugation

Question 10

Which of the following statements about the polarity of 1,2-dichlorobenzene is correct?

Accepted Answer

It is polar, with the dipole moment pointing between the two chlorine atoms

Question 11

What is the electron geometry and hybridization of the oxygen atom in HCN?

Accepted Answer

There is no oxygen atom in HCN

Question 12

Which of the following best describes the difference between constitutional isomers and stereoisomers?

Accepted Answer

Constitutional isomers have different connectivity; stereoisomers have the same connectivity but differ in spatial arrangement

Question 13

Which of the following molecules will have the largest dipole moment?

Accepted Answer

HCN

Question 14

Which of the following is true about the most stable Newman projection of 1,1-dibromopropane?

Accepted Answer

The two Br atoms are anti to each other, minimizing steric repulsion

Question 15

Which resonance structure of para-chloroaniline contributes least to the resonance hybrid?

Accepted Answer

The structure with a positive charge on nitrogen

Question 16

Which bond in the following molecule is expected to be the shortest?

A) C–C single bond
B) C=C double bond
C) C≡C triple bond
D) C–H bond

Accepted Answer

C) C≡C triple bond

Question 17

How many secondary carbons are present in 2,3-dimethylhexane?

Accepted Answer

5

Question 18

Which of the following statements about the hybridization of the carbon atom in benzene is correct?

Accepted Answer

Each carbon atom is sp$$^2$$ hybridized

Question 19

Which of the following is the correct IUPAC name for the structure shown in question 6B (isopropyl group attached to 2,2-dimethylbutane)?

Accepted Answer

2-isopropyl-2,3-dimethylpentane

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