Question

final exam - requires respondus lockdown browser + webcam
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which formula is incorrectly matched with its vsepr model representation? (note: lone pairs on the models, if any, are not shown.)
a) cs₂:
b) sf₆:
c) so₂:
d)
nh₃:

Explanation:

Step1: Analyze \( CS_2 \) (Option A)

\( CS_2 \) has a linear structure (like \( CO_2 \)) with \( C \) as the central atom, sp - hybridized. The model shows a linear arrangement, which matches.

Step2: Analyze \( SF_6 \) (Option B)

\( SF_6 \) has an octahedral geometry (6 bonding pairs, no lone pairs on \( S \)). The model shows 6 atoms around the central atom in octahedral arrangement, which matches.

Step3: Analyze \( SO_2 \) (Option C)

\( SO_2 \) has a bent (V - shaped) structure. The central \( S \) has 2 bonding pairs and 1 lone pair (or resonance, but electron - domain geometry is trigonal planar, molecular geometry bent). The model here shows a bent structure? Wait, no, wait the model for \( SO_2 \) in the image: Wait, no, let's re - check \( NH_3 \) (Option D).

Step4: Analyze \( NH_3 \) (Option D)

\( NH_3 \) has a trigonal pyramidal geometry (central \( N \) has 3 bonding pairs and 1 lone pair). The model shown for \( NH_3 \) appears to be a trigonal planar (or maybe a different geometry). Wait, no, the model for \( NH_3 \): Wait, the model for \( NH_3 \) in the image: Let's count the atoms. \( NH_3 \) has 3 \( H \) atoms around \( N \). The model shown for \( D \) (labeled \( NH_3 \)) has a trigonal planar - like arrangement? Wait, no, \( NH_3 \) is trigonal pyramidal. Wait, maybe I made a mistake. Wait, let's re - evaluate each:

Wait, the question is which formula is incorrectly matched. Let's check each:

- \( CS_2 \): Linear, model is linear - correct.
- \( SF_6 \): Octahedral, model is octahedral - correct.
- \( SO_2 \): Bent, model - let's see the model for \( SO_2 \) (Option C) has a bent structure? Wait, no, the model for \( NH_3 \) (Option D): \( NH_3 \) should have a trigonal pyramidal shape (3 \( H \) atoms and one lone pair on \( N \)). The model shown for \( NH_3 \) in the image has a trigonal planar arrangement (like \( BF_3 \))? Wait, no, the model for \( D \) ( \( NH_3 \)): looking at the image, the \( NH_3 \) model has three atoms bonded to the central atom in a trigonal planar (or maybe a different) but \( NH_3 \) is trigonal pyramidal. Wait, maybe the error is in \( NH_3 \). Wait, no, let's check the number of atoms. \( NH_3 \) has 3 \( H \) atoms. The model for \( D \) ( \( NH_3 \)): in the image, the model for \( D \) has three atoms? Wait, no, the model for \( D \) (labeled \( NH_3 \)): looking at the image, the model for \( D \) has a central atom with three atoms bonded, but in a trigonal planar? Wait, no, \( NH_3 \) is trigonal pyramidal. Wait, maybe the model for \( NH_3 \) is incorrect. Wait, but let's re - check the options. Wait, the model for \( NH_3 \) (Option D) in the image: if the model shows a trigonal planar (like \( BH_3 \)) instead of trigonal pyramidal, then it's incorrect. But wait, maybe I mislabeled. Wait, the option D is labeled \( NH_3 \). The model for D has a central atom with three atoms bonded in a trigonal planar (or maybe a different) arrangement. Wait, no, \( NH_3 \) has a lone pair, so molecular geometry is trigonal pyramidal. The model shown for \( NH_3 \) in the image seems to have a trigonal planar (no lone pair shown, but the geometry is wrong). Wait, but let's check the other options again.

Wait, \( SO_2 \): central \( S \), 2 double bonds (or 1 double and 1 single with resonance), electron - domain geometry trigonal planar (3 domains: 2 bonding, 1 lone pair), molecular geometry bent. The model for \( SO_2 \) (Option C) shows a bent structure? Maybe. Wait, the key is \( NH_3 \): \( NH_3 \) has a trigonal pyramidal geometry. The model for \( NH_3 \) (Option D) in the image: if the model is showing a trigonal planar (like \( BF_3 \)) then it's incorrect. Wait, maybe the model for \( NH_3 \) is incorrect. So the answer is D.

Answer:

D. \( NH_3 \)