Question 1

Which of the following is the most likely Lewis structure for $$\mathrm{C_2H_2} ($$acetylene)?

Accepted Answer

A structure with a triple bond between the two carbons and each carbon bonded to one hydrogen.

Question 2

What are the formal charges on nitrogen and on the starred oxygen in the following species: $$\mathrm{CH_3N(O)O^*} ($$where $$O^* is $$the oxygen with a single bond to nitrogen and three lone pairs)?

Accepted Answer

$$\mathrm{N = +1,\ O^* = 0}$$

Question 3

How many sigma ($$\sigma) $$and pi ($$\pi) $$bonds are present in $$\mathrm{CH_3CN} ($$acetonitrile)?

Accepted Answer

$$5\ \sigma$$ bonds and $$2\ \pi$$ bonds

Question 4

Which carbons in the following compound are $$sp$$ hybridized? $$\mathrm{CH_3COCH_2C \equiv CH} ($$numbered 1 to 5 from left to right)

Accepted Answer

Carbons 4 and 5

Question 5

Which of the following has an $$sp^2$$ hybridized carbon?

Accepted Answer

A methyl carbocation ($$\mathrm{CH_3$^+})$$

Question 6

The N-H bond in the ammonium ion ($$\mathrm{NH_4$^+}) is $$formed by the overlap of which two orbitals?

Accepted Answer

$$sp^3 (N) $$and $$s (H)$$

Question 7

Which of the following angles is closest to the C-O-C bond angle in dimethyl ether ($$\mathrm{CH_3$-O-CH_3$}$$)?

Accepted Answer

$$109.5^\circ$$

Question 8

Which of the following compounds has a dipole moment of zero?

Accepted Answer

trans-1,2-dichloroethene

Question 9

Which of the following best describes the direction of the polarity in the O-H bond of methanol ($$\mathrm{CH_3OH}$$)?

Accepted Answer

From O to H, with O being $$\delta^-$$ and H being $$\delta^+$$

Question 10

Which of the following condensed structures corresponds to pentane?

Accepted Answer

$$\mathrm{CH_3$(CH_2$)_3CH_3}$$

Question 11

Which of the following best represents the Lewis structure for formaldehyde ($$\mathrm{CH_2O}$$)?

Accepted Answer

A structure with a double bond between C and O, and two single bonds between C and H.

Question 12

Which of the following is the correct expanded structure for $$\mathrm{(CH_3$)_2CHCH_2CHO}$$?

Accepted Answer

A structure with two methyl groups attached to a central carbon, which is attached to a methylene group and an aldehyde group.

Question 13

Which of the following best describes the orbital overlap in a $$\pi$$ bond?

Accepted Answer

Side-to-side overlap of unhybridized $$p$$ orbitals

Question 14

Which of the following best describes the hybridization of the carbon atom in methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

$$sp^3$$

Question 15

Which of the following is the correct Lewis structure for the methyl anion ($$\mathrm{CH_3$^-}$$)?

Accepted Answer

A carbon atom with three single bonds to hydrogen and one lone pair, with a negative charge on carbon.

Question 16

Which of the following best describes the geometry around the oxygen atom in water ($$\mathrm{H_2O}$$)?

Accepted Answer

Bent, with a bond angle of approximately $$104.5^\circ$$

Organic Chemistry: Lewis Structures, Hybridization, and Molecular Properties

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