To determine the shape of ${\mathrm{SF}}_4$, we first need to find its hybridization and the number of lone pairs on the central sulfur atom using VSEPR theory.

Step 1: Determine the total number of valence electrons.
Sulfur (S) is in Group 16, so it has 6 valence electrons.
Fluorine (F) is in Group 17, so it has 7 valence electrons.
Total valence electrons = $6+4\times 7=6+28=34$ electrons.

Step 2: Determine the number of bond pairs and lone pairs.
In ${\mathrm{SF}}_4$, sulfur is the central atom. It forms 4 single bonds with 4 fluorine atoms.
Number of bond pairs = 4.
Electrons used in bonding = $4\times 2=8$ electrons.
Remaining electrons = $34-8=26$ electrons. These are distributed as lone pairs on fluorine atoms (3 lone pairs each, $4\times 3\times 2=24$ electrons) and on the central sulfur atom.
Electrons remaining for central atom = $26-24=2$ electrons.
Number of lone pairs on sulfur = $2/2=1$ lone pair.

Step 3: Determine the steric number and hybridization.
Steric number = Number of bond pairs + Number of lone pairs = $4+1=5$.
A steric number of 5 corresponds to ${\mathrm{sp}}^3\mathrm{d}$ hybridization.

Step 4: Determine the electron geometry and molecular shape.
For a steric number of 5, the electron geometry is trigonal bipyramidal. With 4 bond pairs and 1 lone pair, the lone pair occupies an equatorial position to minimize repulsion. This arrangement results in a distorted tetrahedral shape, which is commonly known as a see-saw shape.

Option Analysis:

• A) tetrahedral: This shape occurs with 4 bond pairs and 0 lone pairs (e.g., ${\mathrm{CH}}_4$). ${\mathrm{SF}}_4$ has 1 lone pair.
• B) square planar: This shape occurs with 4 bond pairs and 2 lone pairs (e.g., ${\mathrm{XeF}}_4$) or 4 bond pairs and 0 lone pairs in some transition metal complexes. ${\mathrm{SF}}_4$ has 1 lone pair.
• C) trigonal pyramid: This shape occurs with 3 bond pairs and 1 lone pair (e.g., ${\mathrm{NH}}_3$). ${\mathrm{SF}}_4$ has 4 bond pairs and 1 lone pair.
• D) see-saw: This is the correct shape for a molecule with 4 bond pairs and 1 lone pair, derived from a trigonal bipyramidal electron geometry.

Correct Answer: (D)