Question 1

Which of the following compounds, all of which have the molecular formula C₆H₁₂, has cis and trans isomers?

Accepted Answer

The compounds given in the question have a formula that suggests that they are unsaturated hydrocarbons with one sulfur, one hydrogen, and 16 carbon atoms. This means that we are dealing with an alkene, specifically, a C16 alkene with one sulfur and one hydrogen substituent. The only compound among the given options that fits this description is 3-methyl-2-pentene. This compound has a double bond between carbon atoms 2 and 3, so there are two possible arrangements of the substituent groups around this double bond: one in which both methyl groups are on the same side of the double bond (cis), and one in which they are on opposite sides (trans). Therefore, the correct answer is C, which is the only compound among the given options that can have cis and trans isomers.

Question 2

Which of the following is not a correct IUPAC name for an alkene?

Accepted Answer

The prefix "1-" is used when there are multiple substituents on the same carbon chain, but in this case, there is only one substituent (methyl group) attached to the butene chain. Therefore, the correct name should be "2-methyl-1-butene", "3-methyl-1-butene", or "2-methyl-2-butene".

Question 3

A student wanted to use the branched groups, isobutyl, sec-butyl, and tert-butyl when naming alkenes, but was told not to. What is the correct IUPAC name for the compound the student called isobutylethene?

Accepted Answer

The answer of A student wanted to use the branched...

Question 4

Cis-trans isomers do not exist for which of the following compounds, all of which have the molecular formula C₃H₄Br₂?

Accepted Answer

1,1-dibromopropene does not have cis-trans isomers because the two bromine atoms are attached to the same carbon atom, preventing the formation of geometric isomers.

Question 5

Which of the following, all of which have the molecular formula C₅H₁₀, has cis and trans isomers?

Accepted Answer

2-pentene has a double bond between the second and third carbon atoms, allowing for the possibility of cis and trans isomers due to the different spatial arrangements of the substituents around the double bond.

Question 6

Which of the following compounds, all of which have the molecular formula C₆H₁₂, does not have cis and trans isomers?

Accepted Answer

The molecular formula given does not indicate any double bonds or stereochemistry. Therefore, all of the compounds listed are capable of having cis and trans isomers. The correct answer is B because it is not listed among the given compounds.

Question 7

A student named a particular compound 2-propyl-1-butene. Assuming that the student's choice actually corresponded to the correct distribution of the double bond and the substituents, what is the correct IUPAC name for this compound?

Accepted Answer

The correct IUPAC name for the compound described is 2-ethyl-1-pentene. This is because the longest carbon chain that includes the double bond has five carbons, making it a pentene, and the substituent is an ethyl group at the 2-position, not a propyl group.

Question 8

Which of the following structures corresponds to cis-3-methyl-2-hexene?

Accepted Answer

The answer of Which of the following structures corresponds to...

Question 9

Which of the following is true of the common names of low molecular weight alkenes and alkynes?

Accepted Answer

The answer of Which of the following is true of...

Question 10

A student wanted to use the branched groups, isobutyl, sec-butyl, and tert-butyl when naming alkenes, but was told not to. What is the correct IUPAC name for the compound the student called sec-butylethene?

Accepted Answer

The correct IUPAC name for sec-butylethene is 3-methyl-1-pentene because the sec-butyl group is not used in naming alkenes according to IUPAC rules. Instead, the alkene is numbered to give the lowest possible number to the carbon of the double bond, which in this case is the first carbon of the five-carbon chain. The methyl group is then located at the third carbon, giving the name 3-methyl-1-pentene.

Question 11

Which of the following is not a correct IUPAC name for an alkene?

Accepted Answer

2-methyl-3-butene is not a correct IUPAC name because the longest carbon chain that includes the double bond would be numbered to give the double bond the lowest possible number, making the correct name 3-methyl-1-butene instead.

Question 12

Cis-trans isomers exist for which of the following molecules, all of which have the molecular formula C₃H₅Br?

Accepted Answer

The answer of Cis-trans isomers exist for which of the...

Question 13

What is the correct IUPAC name for the following compound?

Accepted Answer

The compound has a double bond between the second and third carbon atoms, so the parent chain is a pentene. There are two methyl groups attached to the fourth carbon atom, so the correct name is 4,4-dimethyl-1-pentene. option A and B have an incorrect position of the double bond and option D has an incorrect number of Carbon atoms.

Question 14

What is the correct IUPAC name for the following compound?

Accepted Answer

The longest carbon chain contains six carbons, giving the parent hydrocarbon the name hexene. The double bond is located between carbons 2 and 3, giving the suffix -2-ene. There are two methyl groups on carbon 2 and one methyl group on carbon 3, giving the name 2,3-dimethyl-2-hexene. Neither propyl nor pentyl groups are present in the compound, eliminating choices A and B.

Question 15

Cis-trans isomers exist for which of the following molecules, all of which have the molecular formula C₅H₁₀?

Accepted Answer

Cis-trans isomerism occurs in alkenes or cyclic compounds where there is restricted rotation around a bond. 1,2-dimethylcyclopropane is a cyclic compound that can exhibit cis-trans isomerism due to the fixed positions of the substituents on the ring.

Question 16

Which of the following is true in the IUPAC system for naming alkenes?

Accepted Answer

In the IUPAC system for naming alkenes, the position of the double bond is always given the lowest possible number. This means that the numbering of the carbons in the longest carbon chain that contains the double bond must start at the end closest to the double bond, even if it means giving a higher number to a substituent. The alkene is then named based on the name of the parent carbon chain, with the suffix -ene indicating the presence of a double bond. The position and identity of any substituents are indicated using numbers that correspond to the carbons to which they are attached.

Question 17

What is the correct IUPAC name for the following compound?

Accepted Answer

The answer of What is the correct IUPAC name for...

Question 18

What is the name of the lightest hydrocarbon which has cis and trans isomers?

Accepted Answer

2-butene is the lightest hydrocarbon which has cis (Z) and trans (E) isomers. It has a molecular weight of 56.11 g/mol and consists of four carbon atoms and eight hydrogen atoms. The other options do not have cis-trans isomers.

Question 19

Which of the following is not a correct IUPAC name for an alkene?

Accepted Answer

All of the choices given are correct IUPAC names for alkenes.

Question 20

A student named a particular compound 2-ethyl-3-methyl-2-butene. Assuming that the student's choice actually corresponded to the correct distribution of the double bond and the substituents, what is the correct IUPAC name for this compound?

Accepted Answer

The correct IUPAC name for this compound is 2,3-dimethyl-2-butene. The carbon chain is numbered from the end closest to the double bond, giving the double bond the lowest possible number. The two methyl groups are on the second carbon, and the ethyl group is on the third carbon. Butene indicates that there are four carbons, and the placement of the double bond at the second and third carbons results in the name 2-butene. The two methyl substituents are then indicated by the 2,3-dimethyl prefix. Therefore, option C is the correct choice.

Quiz 12: Alkenes and Alkynes

Which of the following compounds, all of which have the molecular formula C6H12, has cis and trans isomers?

Which of the following is not a correct IUPAC name for an alkene?

A student wanted to use the branched groups, isobutyl, sec-butyl, and tert-butyl when naming alkenes, but was told not to. What is the correct IUPAC name for the compound the student called isobutylethene?

Cis-trans isomers do not exist for which of the following compounds, all of which have the molecular formula C3H4Br2?

Which of the following, all of which have the molecular formula C5H10, has cis and trans isomers?

Which of the following compounds, all of which have the molecular formula C6H12, does not have cis and trans isomers?

A student named a particular compound 2-propyl-1-butene. Assuming that the student's choice actually corresponded to the correct distribution of the double bond and the substituents, what is the correct IUPAC name for this compound?

Which of the following structures corresponds to cis-3-methyl-2-hexene?

Which of the following is true of the common names of low molecular weight alkenes and alkynes?

A student wanted to use the branched groups, isobutyl, sec-butyl, and tert-butyl when naming alkenes, but was told not to. What is the correct IUPAC name for the compound the student called sec-butylethene?

Which of the following is not a correct IUPAC name for an alkene?

Cis-trans isomers exist for which of the following molecules, all of which have the molecular formula C3H5Br?

What is the correct IUPAC name for the following compound?

What is the correct IUPAC name for the following compound?

Cis-trans isomers exist for which of the following molecules, all of which have the molecular formula C5H10?

Which of the following is true in the IUPAC system for naming alkenes?

What is the correct IUPAC name for the following compound?

What is the name of the lightest hydrocarbon which has cis and trans isomers?

Which of the following is not a correct IUPAC name for an alkene?

A student named a particular compound 2-ethyl-3-methyl-2-butene. Assuming that the student's choice actually corresponded to the correct distribution of the double bond and the substituents, what is the correct IUPAC name for this compound?

Which of the following compounds, all of which have the molecular formula C₆H₁₂, has cis and trans isomers?

Cis-trans isomers do not exist for which of the following compounds, all of which have the molecular formula C₃H₄Br₂?

Which of the following, all of which have the molecular formula C₅H₁₀, has cis and trans isomers?

Which of the following compounds, all of which have the molecular formula C₆H₁₂, does not have cis and trans isomers?

Cis-trans isomers exist for which of the following molecules, all of which have the molecular formula C₃H₅Br?

Cis-trans isomers exist for which of the following molecules, all of which have the molecular formula C₅H₁₀?