To determine the correct IUPAC names for the compounds CH3COOH and CH2=CH2, let's analyze each compound step by step. ### Step 1: Identify the Compounds 1. **CH3COOH**: This compound is known as acetic acid. It consists of a methyl group (CH3) attached to a carboxylic acid functional group (COOH). The presence of the carboxylic acid group (-COOH) is key to identifying this compound as an acid. 2. **CH2=CH2**: This compound is known as ethene. It is a simple alkene with a double bond between two carbon atoms. The presence of the double bond is what classifies it as an alkene. ### Step 2: Determine the IUPAC Names - **For CH3COOH (Acetic Acid)**: - The longest carbon chain that includes the carboxylic acid group has two carbon atoms. The carboxylic acid is given priority in naming, and the suffix "-oic acid" is used. - The name is derived from the root name for two carbon atoms, which is "ethane." When we replace the "e" with "oic acid," we get "acetic acid." - **For CH2=CH2 (Ethene)**: - 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 change the suffix to "-ene," resulting in "ethene." ### Step 3: Evaluate the Options Now, let's evaluate the provided options: - **A. acetic acid and ethene**: This option correctly identifies CH3COOH as acetic acid and CH2=CH2 as ethene. Therefore, this option is correct. - **B. methanoic acid and ethene**: This option incorrectly names CH3COOH as methanoic acid. Methanoic acid (HCOOH) has only one carbon atom, while acetic acid has two. Thus, this option is incorrect. - **C. acetic acid and ethene**: This option is identical to option A and is also correct. However, since we are looking for the best answer, we will consider A as the primary correct option. - **D. acetic acid and ethane**: This option incorrectly identifies CH2=CH2 as ethane. Ethane (C2H6) has only single bonds between carbon atoms, while CH2=CH2 has a double bond, making it ethene. Therefore, this option is incorrect. ### Summary of the Correct Answer The correct answer is **A. acetic acid and ethene**. ### Common Pitfalls - Confusing methanoic acid (HCOOH) with acetic acid (CH3COOH) due to similar names. - Misidentifying alkenes (like ethene) as alkanes (like ethane) by overlooking the presence of double bonds. ### Revision Summary - **CH3COOH is acetic acid**: Recognized by the carboxylic acid functional group. - **CH2=CH2 is ethene**: Identified by the double bond between two carbon atoms. - **Correct IUPAC naming**: Understand the importance of functional groups and carbon chain length in naming. - **Avoid common mistakes**: Differentiate between similar-sounding compounds and recognize the significance of double bonds in alkenes.