The correct option for the IUPAC names of the compounds CH3COOH and CH2=CH2 is **A. acetic acid and ethene**. Let's break down why this is the correct answer and analyze the other options. ### Step-by-Step Explanation 1. **Identifying the Compounds**: - **CH3COOH**: This compound is known as acetic acid. It consists of a methyl group (CH3) attached to a carboxylic acid group (COOH). The presence of the carboxylic acid functional group (-COOH) is key to identifying it as an acid. - **CH2=CH2**: This compound is known as ethene. It is an alkene, characterized by a double bond between the two carbon atoms (C=C). 2. **IUPAC Naming Rules**: - For **CH3COOH**: - The longest carbon chain that includes the carboxylic acid group is two carbons long (C1 and C2). - The carboxylic acid functional group takes precedence in naming, leading to the suffix “-oic acid”. - Therefore, the name is derived from the parent alkane (ethane) by replacing the “-e” with “-oic acid”, resulting in **acetic acid**. - For **CH2=CH2**: - This compound has two carbon atoms connected by a double bond. - The base name for two carbon atoms is “ethane”, but since there is a double bond, we use the suffix “-ene”. - Thus, the name becomes **ethene**. 3. **Why Option A is Correct**: - Option A correctly identifies CH3COOH as acetic acid and CH2=CH2 as ethene, aligning with the IUPAC naming conventions. ### Analysis of Other Options - **Option B: methanoic acid and ethene** - **Methanoic acid** refers to HCOOH (formic acid), which has only one carbon atom. Since CH3COOH has two carbon atoms, this option is incorrect. - **Option C: methanoic acid and ethylene** - Similar to Option B, methanoic acid (HCOOH) is incorrect for CH3COOH. Additionally, while ethylene is an older name for ethene, it is not the IUPAC name. Therefore, this option is also incorrect. - **Option D: ethanol and ethene** - **Ethanol** (C2H5OH) is an alcohol, which is not the correct classification for CH3COOH. This option misidentifies the first compound, making it incorrect. ### Summary of Key Points - **CH3COOH** is correctly named **acetic acid** due to its carboxylic acid functional group. - **CH2=CH2** is correctly named **ethene** because it has a double bond between two carbon atoms. - The other options incorrectly identify the compounds based on their structures and functional groups. ### Revision Summary - Acetic acid (CH3COOH) has a carboxylic acid group and is derived from ethane. - Ethene (CH2=CH2) is an alkene with a double bond between two carbon atoms. - Always identify the functional groups and longest carbon chains when naming compounds. - Familiarize yourself with IUPAC naming conventions to avoid common pitfalls.