See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1: Identify the structure. The compound is CH2=CH-CH(CH3)2, which contains a double bond and a branched carbon chain. Step 2: Find the longest carbon chain that includes the double bond. The main chain consists of: CH2=CH-CH- with two methyl groups on the last carbon. Counting carbons in the longest chain including the double bond: C1(CH2=)-C2(CH=)-C3(CH)-C4(CH3), giving a 4-carbon chain (but-1-ene as parent) with a methyl substituent. Wait, let me re-examine: CH2=CH-CH(CH3)2 has C1=C2-C3 where C3 bears two CH3 groups. The longest chain including the double bond: if we take one of the CH3 groups as part of the chain, we get C1=C2-C3-C4, which is a 4-carbon chain (butene). The other CH3 becomes a methyl substituent at C3. Step 3: Number the chain to give the double bond the lowest locant. Numbering from the CH2= end: C1=C2-C3(CH3)-C4. This gives the double bond at position 1 (but-1-ene) and a methyl group at position 3. Step 4: Assign the name. Parent chain: but-1-ene. Substituent: 3-methyl. Full name: 3-Methylbut-1-ene. Step 5: Evaluate other options. - (a) 1,1-Dimethylprop-2-ene would be (CH3)2C-CH=CH2 numbered differently, but this naming is incorrect for this structure. - (c) 2-Vinylpropane is a common/trivial name, not an IUPAC name. - (d) none of these is incorrect since (b) is valid. Therefore, the correct answer is B.