When an alkane reacts with chlorine in a substitution reaction, a hydrogen atom is replaced by a chlorine atom.
Correct Answer
True
True. Alkanes have no multiple bonds to add across, so their typical reaction with halogens is substitution, as when methane and chlorine form chloromethane and HCl.
Category: Alkanes
Question 2
The two carbon atoms of a carbon-carbon double bond are sp3 hybridized.
Correct Answer
False
False. The carbons of a double bond are sp2 hybridized. Each has three sigma bonds in a plane and one unhybridized p orbital that forms the pi bond.
Category: Alkenes and Alkynes
Question 3
The carbon atoms of a carbon-carbon triple bond are sp hybridized, giving a linear arrangement.
Correct Answer
True
True. Each carbon in a triple bond uses two sp hybrid orbitals for sigma bonds 180 degrees apart, and two unhybridized p orbitals form two pi bonds.
Category: Alkenes and Alkynes
Question 4
In naming a branched alkane, the parent chain is the shortest continuous chain of carbon atoms.
Correct Answer
False
False. The parent chain is the longest continuous chain of carbon atoms. Branches are then named as substituents and numbered from the end of the chain nearer the first branch.
Category: Alkanes
Question 5
Alkenes are generally more reactive than alkanes because the pi bond of a double bond can be broken in addition reactions.
Correct Answer
True
True. The pi bond is weaker than a sigma bond and its electrons are exposed above and below the plane of the molecule, so reagents such as H2, Br2 and water can add across it.
Category: Alkenes and Alkynes
Question 6
The pi bond in an alkene forms from the end-to-end overlap of hybrid orbitals.
Correct Answer
False
False. A pi bond forms from the side-by-side overlap of unhybridized p orbitals. End-to-end overlap of orbitals forms a sigma bond.
Category: Alkenes and Alkynes
Question 7
Benzene is an aromatic hydrocarbon with the molecular formula C6H6.
Correct Answer
True
True. Benzene is a six-carbon ring with one hydrogen on each carbon and six pi electrons delocalized around the ring.
Category: Aromatic Compounds
Question 8
In a tertiary alcohol, the carbon bearing the -OH group is bonded to only one other carbon atom.
Correct Answer
False
False. In a tertiary alcohol, the carbon bearing the -OH group is bonded to three other carbon atoms. Because that carbon has no hydrogen, tertiary alcohols resist oxidation.
Category: Alcohols and Ethers
Question 9
Ethers such as diethyl ether are widely used as solvents for fats, waxes and other nonpolar substances.
Correct Answer
True
True. Ethers dissolve many nonpolar and slightly polar organic substances, which makes them useful laboratory and industrial solvents. Diethyl ether is also very volatile and highly flammable.
Category: Alcohols and Ethers
Question 10
Ethylene glycol, used in automobile antifreeze, is an alcohol with three hydroxyl groups.
Correct Answer
False
False. Ethylene glycol has two hydroxyl groups, one on each of its two carbons. Glycerol is the common alcohol with three hydroxyl groups.
Category: Alcohols and Ethers
Question 11
Many esters have pleasant, fruity odors and are responsible for the scents of fruits and flowers.
Correct Answer
True
True. Esters contribute the odors of fruits such as apples, raspberries and strawberries, and they are used as artificial flavorings and fragrances.
Category: Carbonyl Compounds
Question 12
Carboxylic acids such as acetic acid are strong acids that ionize completely in water.
Correct Answer
False
False. Carboxylic acids are weak acids; only a small fraction of the dissolved molecules ionize, for example about 1 percent in 0.1 M acetic acid.
Category: Carbonyl Compounds
Question 13
The carbonyl group is polar because oxygen is more electronegative than carbon.
Correct Answer
True
True. Oxygen pulls electron density toward itself, leaving the carbonyl carbon partially positive. That partial positive charge is where Lewis bases tend to react.
Category: Carbonyl Compounds
Question 14
Oxidation of an alcohol replaces a C-O bond with a C-H bond.
Correct Answer
False
False. In organic chemistry, oxidation replaces a C-H bond with a C-O bond. Replacing a C-O bond with a C-H bond is a reduction.
Category: Carbonyl Compounds
Question 15
Aldehydes are easily oxidized to carboxylic acids.
Correct Answer
True
True. The hydrogen on the carbonyl carbon of an aldehyde can be replaced by an -OH group, converting the aldehyde into a carboxylic acid. Ketones lack that hydrogen and resist this oxidation.
Category: Carbonyl Compounds
Question 16
Methanal, HCHO, is the simplest ketone.
Correct Answer
False
False. Methanal, commonly called formaldehyde, is the simplest aldehyde. The simplest ketone is acetone, CH3COCH3, which has a carbonyl group between two carbons.
Category: Carbonyl Compounds
Question 17
Diethyl ether was once widely used as a general anesthetic in surgery.
Correct Answer
True
True. Diethyl ether was first used as a surgical anesthetic in the 1840s. It has since been replaced by safer anesthetics that are less flammable.
Category: Alcohols and Ethers
Question 18
Hexane dissolves readily in water because hexane molecules are highly polar.
Correct Answer
False
False. Hexane is a nonpolar hydrocarbon, so it does not mix with polar water. Hydrocarbons dissolve in nonpolar solvents instead.
Category: Alkanes
Question 19
The peptide bonds that join amino acids in proteins are amide linkages.
Correct Answer
True
True. A peptide bond forms when the carboxyl group of one amino acid reacts with the amino group of another and water is released, producing an amide.
Category: Amines and Amides
Question 20
A carbon atom typically forms three covalent bonds in organic compounds.
Correct Answer
False
False. Carbon has four valence electrons and typically forms four covalent bonds, which can be single, double or triple bonds in various combinations.
Category: Alkanes