Let's break down each compound step by step and draw their **skeletal or condensed structures**. --- ### a. **2-ethyl-3-t-butylhexane** #### **Step 1: Identify the parent chain** - The parent chain is **hexane** (6 carbons, straight chain). #### **Step 2: Number the chain** - Number from the left, so that the substituents get the lowest possible numbers. #### **Step 3: Identify substituents** - At **C-2**: **ethyl group** (–CH₂CH₃) - At **C-3**: **t-butyl group** (–C(CH₃)₃) #### **Step 4: Draw the skeletal structure** **Skeletal Structure:** ``` CH3 | CH3CH2-C-CH-CH2-CH2-CH3 | | CH2CH3 t-butyl ``` But let's be more precise using skeletal line structure: 1. Draw a six-carbon chain (hexane). 2. At C-2 (second carbon from left), attach an ethyl group. 3. At C-3, attach a tert-butyl group. **Numbering:** ``` 1 2 3 4 5 6 |----|----|----|----|----| C1 - C2 - C3 - C4 - C5 - C6 | | Et t-Bu ``` #### **Condensed Structural Formula:** **Condensed:** ``` CH3CH(CH2CH3)CH(C(CH3)3)CH2CH2CH3 ``` #### **Skeletal Structure Drawing:** ``` Et t-Bu | | CH3-CH-CH-CH2-CH2-CH3 ``` (where "Et" is –CH₂CH₃ and "t-Bu" is –C(CH₃)₃) --- ### b. **cis-3-isopropyl-1-ethylcyclopentane** #### **Step 1: Draw the parent ring** - Cyclopentane (5-membered ring). #### **Step 2: Number the ring** - Number so that the substituents get the lowest numbers: - C-1: ethyl - C-3: isopropyl #### **Step 3: Draw substituents** - At C-1: ethyl group (–CH₂CH₃) - At C-3: isopropyl group (–CH(CH₃)₂) - **cis** configuration: both substituents are on the same side of the ring (both wedges or both dashes). #### **Skeletal Structure Drawing:** ``` 3 (isopropyl) / \ / \ 2 4 \ / 1---5 (ethyl) - At C-1, draw an ethyl group as a bold wedge. - At C-3, draw an isopropyl group as a bold wedge (both on the same side = cis). ``` #### **Condensed Structural Formula:** - **Condensed:** **cis-1-ethyl-3-isopropylcyclopentane** (showing the ring with substituents on the same side) **Structure:** ``` (drawn as a ring) CH(CH3)2 | __|__ / \ CH2CH3 | \ / ----- (ethly and isopropyl groups both on wedges) ``` --- ## **Final Answers** ### **a. 2-ethyl-3-t-butylhexane** **Condensed Formula:** ``` CH3CH(CH2CH3)CH(C(CH3)3)CH2CH2CH3 ``` **Skeletal Structure:** ``` (CH2CH3) | CH3-CH-CH-CH2-CH2-CH3 | (C(CH3)3) ``` ### **b. cis-3-isopropyl-1-ethylcyclopentane** **Condensed Formula:** ``` cis-1-ethyl-3-isopropylcyclopentane ``` (or) ``` CH(CH3)2 | __ | __ / \ / \ | 3 | | | | \__1---2/5---4__/ | CH2CH3 ``` (**Note:** Both substituents are on the same side/wedge.) --- **Let me know if you want the structures as images.**