Organic Chemistry Practice Questions! Trivia Test

1. Which of the following functional groups contain a carboxyl group?

Esters

Ethers

Carboxylic acids

Aldehydes

Carboxylic acids contain a carboxyl group, which is composed of a carbonyl group (C=O) and a hydroxyl group (-OH) attached to the same carbon atom. This functional group is responsible for the acidic properties of carboxylic acids, as well as their ability to form hydrogen bonds and participate in various chemical reactions. Esters, ethers, and aldehydes do not contain a carboxyl group; instead, they have different functional groups with distinct chemical properties.

Explanation

Carboxylic acids contain a carboxyl group, which is composed of a carbonyl group (C=O) and a hydroxyl group (-OH) attached to the same carbon atom. This functional group is responsible for the acidic properties of carboxylic acids, as well as their ability to form hydrogen bonds and participate in various chemical reactions. Esters, ethers, and aldehydes do not contain a carboxyl group; instead, they have different functional groups with distinct chemical properties.

2. Which of the following is a saturated hydrocarbon?

Structure:

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Explanation

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3. Which of the following structures is a ketone?

Structure:

Structure

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Explanation

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4. -dienes are the name given to compounds with

Exactly one double bond

Exactly one triple bond

Exactly two double bond

More than two double bonds

The correct answer is "exactly two double bonds." The name "dienes" refers to compounds that have exactly two double bonds. This means that there are two carbon-carbon double bonds present in the molecule. It is important to note that if there is only one double bond, the compound would be called a "ene" rather than a "diene." Similarly, if there are more than two double bonds, the compound would have a different name.

Explanation

The correct answer is "exactly two double bonds." The name "dienes" refers to compounds that have exactly two double bonds. This means that there are two carbon-carbon double bonds present in the molecule. It is important to note that if there is only one double bond, the compound would be called a "ene" rather than a "diene." Similarly, if there are more than two double bonds, the compound would have a different name.

5. Name the organic compound below

3,4-diethyl-2-hexene

3,4-ethylhexene

3,4-diethylhexene

3,4-diethyl-4-hexene

The correct answer is 3,4-diethyl-2-hexene because the compound has two ethyl groups (diethyl) attached to the 3rd and 4th carbon atoms of a hexene chain, and the double bond is located between the 2nd and 3rd carbon atoms (2-hexene).

Explanation

The correct answer is 3,4-diethyl-2-hexene because the compound has two ethyl groups (diethyl) attached to the 3rd and 4th carbon atoms of a hexene chain, and the double bond is located between the 2nd and 3rd carbon atoms (2-hexene).

6. Organic compounds in which two hydrocarbon groups are bonded to the same atom of oxygen.

Ether

Alcohol

Ester

Aldehyde

Ether is the correct answer because it is an organic compound in which two hydrocarbon groups are bonded to the same atom of oxygen. Ethers have the general formula R-O-R', where R and R' represent hydrocarbon groups. They are commonly used as solvents and anesthetics due to their low reactivity and volatility.

Explanation

Ether is the correct answer because it is an organic compound in which two hydrocarbon groups are bonded to the same atom of oxygen. Ethers have the general formula R-O-R', where R and R' represent hydrocarbon groups. They are commonly used as solvents and anesthetics due to their low reactivity and volatility.

7. An alkyne with 6 carbons will have how many hydrogen atoms?

10

12

14

13

An alkyne with 6 carbons will have 2 hydrogen atoms bonded to each carbon atom, except for the two end carbon atoms which will have 1 hydrogen atom bonded to each. Therefore, the total number of hydrogen atoms in the alkyne will be 2(6) + 1 + 1 = 13.

Explanation

An alkyne with 6 carbons will have 2 hydrogen atoms bonded to each carbon atom, except for the two end carbon atoms which will have 1 hydrogen atom bonded to each. Therefore, the total number of hydrogen atoms in the alkyne will be 2(6) + 1 + 1 = 13.

8. Which of the following shows a condensation reaction?

Reaction:

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Explanation

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9. What is the name of the organic compound below

3,3-dipropyloctane

3,5-dipropylhexane

3-propyl-5-methyloctane

4-ethyl-6-methylnonane

The compound is named as "4-ethyl-6-methylnonane". It describes a nonane molecule, because the longest chain is 9 carbons long, with an ethyl group attached to the fourth carbon atom and a methyl group attached to the sixth carbon atom along the main carbon chain.

Explanation

The compound is named as "4-ethyl-6-methylnonane". It describes a nonane molecule, because the longest chain is 9 carbons long, with an ethyl group attached to the fourth carbon atom and a methyl group attached to the sixth carbon atom along the main carbon chain.

10. What happens to boiling point and melting point of an organic compound when it exhibits chain branching?

Boiling point increases while melting point decreases

Boiling point decreases while melting point increases

Both boiling point and melting point decreases

Both boiling point and melting point increases

Boiling Point: Chain branching in organic compounds generally leads to a decrease in boiling point. This is because branched-chain molecules have a more compact structure and lower surface area compared to their straight-chain counterparts, resulting in weaker intermolecular forces (van der Waals forces) and, consequently, lower boiling points.

Melting Point: The melting point of branched-chain compounds can be higher than that of their straight-chain counterparts. This is because the compact and often more symmetrical structure of branched molecules can pack more efficiently in the solid state, leading to stronger intermolecular interactions in the solid phase and a higher melting point.

Explanation

Boiling Point: Chain branching in organic compounds generally leads to a decrease in boiling point. This is because branched-chain molecules have a more compact structure and lower surface area compared to their straight-chain counterparts, resulting in weaker intermolecular forces (van der Waals forces) and, consequently, lower boiling points.

Melting Point: The melting point of branched-chain compounds can be higher than that of their straight-chain counterparts. This is because the compact and often more symmetrical structure of branched molecules can pack more efficiently in the solid state, leading to stronger intermolecular interactions in the solid phase and a higher melting point.