VSEPR theory predicts shapes based on electron domains

Steps:

• PCl₅ molecule: Central P bonded to 5 Cl atoms (5 bonding pairs, 0 lone pairs), steric number 5, trigonal bipyramidal shape.
• [PCl₄]⁺ ion: Central P bonded to 4 Cl atoms (+ charge means 4 bonding pairs, 0 lone pairs), steric number 4, tetrahedral shape.
• Solid PCl₅ is ionic ([PCl₄]⁺[PCl₆]⁻), but question specifies PCl₅ molecule (gaseous form) and [PCl₄]⁺ ion.
• Choices do not list trigonal bipyramidal for PCl₅ or confirm tetrahedral for [PCl₄]⁺ accurately.

Not enough information: Choices are ambiguous (C and D identical, none match correct shapes).

Final answer: trigonal bipyramidal, tetrahedral