Question

Which of the following sets are correctly matched? {|c|c|c|} Set & Molecule & Geometry
I & $\text{BrF}_5$ & Square pyramidal
II & $\text{XeF}_6$ & Distorted octahedral
III & $\text{SF}_4$ & Square planar
IV & $\text{PbCl}_2$ & Linear

• A. I and II
• B. II and III
• C. III and IV
• D. I and IV

Hint:

Remember common VSEPR shapes:
• $AX_5E \rightarrow$ Square pyramidal
• $AX_4E \rightarrow$ Seesaw
• $AX_2E \rightarrow$ Bent
• $AX_6E \rightarrow$ Distorted octahedral

Answer 1

The Correct Option is A

Concept: Using VSEPR theory, molecular geometry depends upon:
• Number of bond pairs
• Number of lone pairs
• Steric number of the central atom

Step 1: Analyzing $\text{BrF}_5$.

• Bromine forms 5 bonds and possesses 1 lone pair.
• Steric number $= 6$
• Hybridization $= sp^3d^2$
• Geometry $=$ square pyramidal Hence Set I is correct.

Step 2: Analyzing $\text{XeF}_6$.

• Xenon forms 6 bonds and contains 1 lone pair.
• Steric number $= 7$
• Hybridization $= sp^3d^3$
• Shape $=$ distorted octahedral Hence Set II is correct.

Step 3: Analyzing $\text{SF}_4$.

• Sulfur forms 4 bonds and has 1 lone pair.
• Steric number $= 5$
• Geometry $=$ seesaw It is not square planar. Hence Set III is incorrect.

Step 4: Analyzing $\text{PbCl}_2$.

• Lead contains one lone pair.
• Geometry becomes bent. Therefore it is not linear. Hence Set IV is incorrect.

Step 5: Final conclusion.
Only Sets I and II are correctly matched. Therefore, the correct answer is: \[ \boxed{(a)\ \text{I and II}} \]