Identify the correct name of \( \mathrm{CH}_{3}-\mathrm{C}\left(\mathrm{CH}_{3}\right)_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{3} \). A. 2,2-dimethylbutane B. methylneopentane C. 2-methyl-2-ethylpropane D. 2,2-dimethypentane E. 3,3-dimethybutane 1. A 2. B 3. C 4. D 5. E

The correct answer is **A. 2,2-dimethylbutane**. To break it down, this compound has a four-carbon backbone (butane) with two methyl (-CH₃) groups attached to the second carbon, hence the name 2,2-dimethylbutane. Furthermore, when looking at structural formulas, always remember to examine the longest continuous carbon chain first. This will help you identify the backbone and any substituents correctly. Common mistakes often include miscounting carbon atoms in branched structures or overlooking substituents' positions.