To determine the common name for the compound (CH\(_{3}\))\(_{2}\)CHCH\(_{2}\)-Br, we need to analyze its structure and identify the correct nomenclature. ### Step-by-Step Explanation 1. **Identify the Structure**: - The given compound can be broken down as follows: - (CH\(_{3}\))\(_{2}\) indicates two methyl groups (–CH\(_{3}\)). - CH indicates a carbon atom that is connected to the two methyl groups and another carbon atom. - CH\(_{2}\) indicates a carbon atom that is connected to the previous carbon and also to a bromine atom (–Br). - Therefore, the full structure can be represented as: ``` CH3 | CH3-C-CH2-Br ``` - This structure shows that we have a total of four carbon atoms in a chain, with a bromine atom attached to the last carbon. 2. **Count the Carbon Atoms**: - The total number of carbon atoms in the compound is 4. This is important for naming the compound according to IUPAC rules. 3. **Identify the Longest Carbon Chain**: - The longest continuous chain of carbon atoms in this compound is four carbons long. This is a butane derivative. 4. **Identify the Substituents**: - The bromine atom (–Br) is a substituent on the carbon chain. In this case, it is attached to the terminal carbon (the last carbon in the chain). 5. **Determine the Common Name**: - The common name for a four-carbon alkyl group is "butyl." Since the bromine is attached to the second carbon in the chain (counting from the end closest to the bromine), the compound is specifically known as "isobutyl bromide." - The prefix "iso-" indicates that the compound has a branched structure, which is characteristic of isobutyl groups. ### Evaluating the Options - **Option A: Isobutyl bromide** - This is the correct answer. It accurately describes the structure of the compound as a brominated derivative of isobutane. - **Option B: Methyl bromide** - This is incorrect. Methyl bromide (CH\(_3\)Br) has only one carbon atom and does not match the structure of the given compound. - **Option C: Propyl bromide** - This is also incorrect. Propyl bromide would refer to a three-carbon chain (C\(_3\)H\(_7\)Br), which does not correspond to the four-carbon structure of the compound. - **Option D: Butyl bromide** - While this option is closer, it does not specify the branched nature of the compound. "Butyl bromide" could refer to any butyl group, including straight-chain butyl, which is not the case here. ### Summary of Key Points - The compound (CH\(_{3}\))\(_{2}\)CHCH\(_{2}\)-Br is correctly named **isobutyl bromide** due to its branched structure and the presence of a bromine substituent. - The longest carbon chain contains four carbon atoms, confirming it as a butane derivative. - The presence of the "iso-" prefix indicates a branched structure, distinguishing it from straight-chain butyl compounds. ### Revision Summary - The compound (CH\(_{3}\))\(_{2}\)CHCH\(_{2}\)-Br is named **isobutyl bromide**. - It has a total of four carbon atoms in a branched structure. - The bromine atom is attached to the second carbon in the chain. - Understanding the structure and nomenclature rules is crucial for identifying the correct common name.