Question 14

Shapes: - SOCl2: S has 3 bond pairs + 1 lone pair → trigonal pyramidal. - XeOF4: 5 bond pairs + 1 lone pair → square pyramidal. - ClF3: 3 bp + 2 lp → T-shaped. - ClF5: 5 bp + 1 lp → square pyramidal. - XeF5⁺: 5 bp + 1 lp → square pyramidal. - SO3²⁻: 3 bp + 1 lp → trigonal pyramidal. - XeF3⁺: 3 bp + 2 lp → T-shaped. - SF4: 4 bp + 1 lp → see-saw. Counts: See-saw = 1; T-shaped = 2; Trigonal planar = 0; Square pyramidal = 3. P→1, Q→2, R→5, S→3 → Option A.

No written reasoning was returned for this item.

**Evaluating molecular structure** I'm working through the sulfite ion, SO3^2-. The sulfur has six valence electrons, which gives a total of eight when paired with the oxygens. I think there are three bonds plus one lone pair, leading to a trigonal pyramidal shape instead of trigonal planar. This involves resonance since there's one double bond, but I need to remember there are four electron domains in total!

Checking each species' geometry: SOCl2 is trigonal pyramidal from its lone pair and three bonding groups, so it doesn't fit. XeOF4 comes out square pyramidal with one lone pair on Xe, while ClF3 is T-shaped due to two lone pairs. For SF4, the lone pair gives a see-saw shape, and ClF5 with its single lone pair is square pyramidal like XeOF4. XeF5+ works out to the same square pyramidal arrangement after adjusting for the positive charge, while SO3^2- is pyramidal rather than planar, and XeF3+ turns out T-shaped with two lone pairs. Grouping these: see-saw only fits SF4, T-shaped covers ClF3 and XeF3+, nothing matches trigonal planar, and square pyramidal captures XeOF4, ClF5, and XeF5+ — giving P→1, Q→2, R→zero, S→3, which lines up with option A. Looking at each species: - **SOCl2**: AX3E (S has 3 bonding groups + 1 lone pair) → pyramidal (not in list) - **XeOF4**: AX5E → square pyramidal - **ClF3**: AX3E2 → T-shaped - **ClF5**: AX5E → square pyramidal - **XeF5+**: Xe⁺ (7 valence e⁻), 5 bonds + 1 lone pair → AX5E → square pyramidal - **SO3²⁻**: AX3E → pyramidal (not trigonal planar) - **XeF3+**: Xe⁺ (7 valence e⁻), 3 bonds + 2 lone pairs → AX3E2 → T-shaped - **SF4**: AX4E → see-saw **Counting:** - See-saw: SF4 → **1** - T-shaped: ClF3, XeF3+ → **2** - Trigonal planar: none → **0 (zero)** - Square pyramidal: XeOF4, ClF5, XeF5+ → **3** This matches: P→1, Q→2, R→5, S→3 ```json