Let's solve the problem step by step: ## Step 1: Identify Each Atom's Surroundings Let's look at the atoms labeled **a, b, c, d** in the structure: ``` H H H H | | | | H—C—C—C—C—H | | | | H H H H a b c d ``` - Each letter (a, b, c, d) is on a carbon atom. ## Step 2: Count Number of Groups Around Each Atom Let's count the electron groups (bonds + lone pairs) for each carbon: ### (a) Carbon - Surrounded by 4 atoms (3 H, 1 C) - **4 electron groups** ### (b) Carbon - Surrounded by 4 atoms (2 H, 2 C) - **4 electron groups** ### (c) Carbon - Surrounded by 4 atoms (2 H, 2 C) - **4 electron groups** ### (d) Carbon - Surrounded by 4 atoms (3 H, 1 C) - **4 electron groups** ## Step 3: Assign Electron Geometry The possible geometries are: - **Tetrahedral**: 4 electron groups - **Trigonal Planar**: 3 electron groups - **Linear**: 2 electron groups - **Trigonal Pyramidal**: 4 electron groups, but with one lone pair (like NH₃) - **Square Planar**: 4 bonds, 2 lone pairs (like XeF₄), not relevant for C All carbons here have **4 bonds** (no lone pairs): **4 groups** → **Tetrahedral** ## Step 4: Write Final Answers **(a) Tetrahedral** **(b) Tetrahedral** **(c) Tetrahedral** **(d) Tetrahedral** --- ### **Final Answers** (a) **Tetrahedral** (b) **Tetrahedral** (c) **Tetrahedral** (d) **Tetrahedral**

# Step-by-Step Solution Let's analyze the provided molecular structure and determine the geometry of the specified carbon atoms labeled as **a, b, c,** and **d**. ## Step 1: Visualize the Molecular Structure The molecular structure can be interpreted as follows: ``` H H H H | | | | H—C—C—C—C—H | | | | H H H H a b c d ``` Each letter corresponds to a carbon atom in the chain. ## Step 2: Count Electron Groups Around Each Carbon Atom We will determine the number of electron groups (which include bonds and lone pairs) surrounding each carbon atom: ### Atom (a) - **Bonds**: 1 bond to carbon (C) + 3 bonds to hydrogen (H) - **Total Groups**: 4 ### Atom (b) - **Bonds**: 2 bonds to hydrogens (H) + 2 bonds to adjacent carbons (C) - **Total Groups**: 4 ### Atom (c) - **Bonds**: 2 bonds to hydrogens (H) + 2 bonds to adjacent carbons (C) - **Total Groups**: 4 ### Atom (d) - **Bonds**: 1 bond to carbon (C) + 3 bonds to hydrogens (H) - **Total Groups**: 4 ## Step 3: Determine Electron Geometry Based on the number of electron groups, we can assign the appropriate geometry: - **4 Electron Groups**: This corresponds to a **Tetrahedral** geometry. ### Summary of Geometry Assignments - **(a)**: Tetrahedral - **(b)**: Tetrahedral - **(c)**: Tetrahedral - **(d)**: Tetrahedral ## Final Answers - **(a)**: Tetrahedral - **(b)**: Tetrahedral - **(c)**: Tetrahedral - **(d)**: Tetrahedral This analysis confirms that all specified carbon atoms in the structure exhibit a tetrahedral geometry due to the presence of four electron groups around each carbon atom.