Question: how many carbon atoms are present in one molecule of 2 3 dimethylbutane?
Answer: Thus, the name "2-methylpropane" indicated that there is a three-carbon longest chain, with a one-carbon branch on the second carbon; the name "2,3-dimethylbutane" indicates that there is a four-carbon longest chain, with two one-carbon substituents on carbons 2 and 3.