Question 1

Which of the following statements best describes why carbon is able to form such a wide variety of organic molecules?

Accepted Answer

Carbon has 4 valence electrons and can form four covalent bonds, allowing for single, double, and triple bonds.

Question 2

Which of the following best describes the geometry around a carbon atom with four single bonds, as modeled by the four red balloons in the image?

Accepted Answer

Tetrahedral

Question 3

Which of the following is the correct general formula for an alkane hydrocarbon?

Accepted Answer

$$C_nH_{2n+2}$$

Question 4

A hydrocarbon molecule contains only carbon and hydrogen atoms, and all the carbon-carbon bonds are single bonds. Which class does this molecule belong to?

Accepted Answer

Alkane

Question 5

Which of the following best explains why oil does not dissolve in water, as shown in the image of oil and water in a beaker?

Accepted Answer

Oil is nonpolar and hydrophobic, while water is polar.

Question 6

Which of the following is a structural isomer of pentane ($$C_5H_{12}$$)?

Accepted Answer

A molecule with five carbons in a straight chain and a molecule with four carbons in a chain and one methyl branch

Question 7

Which of the following best describes the type of reaction shown below?

$$CH_2$$=$$CH_2$$ + $$H_2$$ \rightarrow CH_3CH_3$$

Accepted Answer

Addition (hydrogenation)

Question 8

Which of the following molecules would have the highest melting point?

Accepted Answer

$$C_8H_{18}$$

Question 9

Which of the following best describes a cis-trans isomer?

Accepted Answer

Molecules with the same molecular formula and connections, but different spatial arrangements due to restricted rotation around a double bond

Question 10

Which of the following statements about aromatic compounds is TRUE?

Accepted Answer

Aromatic compounds contain a benzene-like ring with alternating double and single bonds, and are planar.

Question 11

Which of the following best explains why double and triple bonds do not rotate freely?

Accepted Answer

The electron density in double and triple bonds is split above and below the bond axis, so rotation would break the pi bonds.

Question 12

Which of the following is the product when water is added across a double bond in an alkene?

Accepted Answer

An alcohol

Question 13

Which of the following best describes the difference between a structural isomer and a conformer?

Accepted Answer

Structural isomers have the same molecular formula but different connections between atoms, while conformers have the same connections but differ by rotation around single bonds.

Question 14

Which of the following best explains why saturated fatty acids have higher melting points than unsaturated fatty acids?

Accepted Answer

Saturated fatty acids pack tightly due to their straight chains, increasing dispersion forces and melting point.

Question 15

Which of the following is NOT a general type of organic reaction?

Accepted Answer

Combustion

Question 16

Which of the following best describes a chiral carbon?

Accepted Answer

A carbon atom with four different groups attached in a tetrahedral geometry

Question 17

Which of the following is a consequence of partial hydrogenation of unsaturated fatty acids in food products?

Accepted Answer

Formation of trans fats, which have properties similar to saturated fats

Question 18

Which of the following best describes a conjugated system?

Accepted Answer

A molecule with alternating double and single bonds, allowing electron density to overlap

Question 19

Which of the following is the most abundant element in the human body by dry weight?

Accepted Answer

Carbon

Question 20

Which of the following best describes the geometry of an alkyne (carbon-carbon triple bond)?

Accepted Answer

Linear

Lecture 5: Hydrocarbons

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