Alkenes Quiz: Alkanes And Alkenes Exam Questions

1-Butanol is not an alkane or alkene because it contains a hydroxyl group (-OH) attached to the first carbon atom. Alkanes and alkenes are hydrocarbons, meaning they only contain carbon and hydrogen atoms. 1-Butanol is an alcohol, which is a different functional group.

Isomerism refers to the phenomenon where certain compounds have the same molecular formula but different structural formulas. This means that they have the same types and numbers of atoms, but the arrangement of these atoms within the molecule is different. Isomers exhibit distinct physical and chemical properties due to their different structural arrangements. This concept is important in organic chemistry as it helps to explain the diversity and complexity of organic compounds.

The general formula of alkanes is CnH2n, while the general formula of alkenes is CnH2n+2: alkanes have twice the number of hydrogen atoms and two additional hydrogen atoms compared to the number of carbon atoms, and alkenes have twice the number of hydrogen atoms as carbon atoms. Therefore, the correct answer is false.

The correct answer is that alkanes are linked together exclusively by single bonds. This means that all the carbon-carbon bonds in alkanes are single bonds, and there are no double or triple bonds present. This characteristic of alkanes makes them relatively stable and unreactive compared to other types of hydrocarbons. Alkanes are saturated hydrocarbons, meaning that they have the maximum number of hydrogen atoms bonded to each carbon atom. The melting and boiling points of alkanes generally increase as the molecular size and complexity increase, rather than decrease down the group.

Alkenes are hydrocarbons that contain at least one carbon-carbon double bond (C=C), making them highly reactive in addition reactions. One common reaction for alkenes is hydrogenation, where hydrogen (H₂) is added across the double bond, converting the alkene into an alkane. This breaks the double bond and forms a single bond between the carbon atoms. In contrast, substitution is more characteristic of alkanes, nitration is a reaction involving aromatic compounds, and elimination typically forms alkenes rather than occurring with them.

The test used to determine where an alkene is present is the Bromine water test. In this test, bromine water is added to the sample. If the sample contains an alkene, the reddish-brown color of the bromine water will be decolorized as the bromine reacts with the alkene to form a colorless compound. This reaction is a characteristic reaction of alkenes, making the Bromine water test a useful tool for their identification.

Naphtha is most unlikely to be a product of cracking because cracking is a process used to break down larger hydrocarbon molecules into smaller ones. Naphtha is a type of hydrocarbon mixture that contains relatively small molecules, so it is not typically produced through cracking. Ethene, propane, and hydrogen gas, on the other hand, are commonly produced as a result of cracking larger hydrocarbon molecules.

Polyunsaturated fats are true fats that have more than one double bond in their carbon chain. These double bonds cause the molecule to lack the maximum number of hydrogen atoms, which is why this statement is true. The other options are incorrect. Polyunsaturated fats actually have a lower melting point compared to saturated fats (allowing polyunsaturated fats to be liquid at room temperature). They contain carbon-carbon double bonds, and they are commonly found in vegetable oils, not lard.

Polymerisation is a process that involves heat, great pressure, and the presence of a catalyst. It is also a free radical reaction. Therefore, the correct answer is both A and C.

A homologous series of organic compounds is a group of compounds that have similar structural formulas, meaning they have the same arrangement of atoms. They also have similar chemical properties, as they have similar functional groups and react in similar ways. Additionally, they have a general formula for the series, which represents the ratio of atoms in the compounds. However, the melting and boiling points may vary within the series due to differences in molecular sizes and intermolecular forces.