The pair having similar geometry is: A. PCl3, NH4+ B. BeCl2, H2O C. CH4, CCl4 D. IF5, PF5

Let's analyze the geometries of the given molecules:

Option A: PCl₃ and NH₄⁺

PCl₃ (Phosphorus trichloride): Phosphorus has 5 valence electrons. Three of these form bonds with chlorine atoms, and one lone pair remains. The molecular geometry is trigonal pyramidal because of the lone pair.
NH₄⁺ (Ammonium ion): Nitrogen forms four bonds with hydrogen atoms and has no lone pairs. The molecular geometry is tetrahedral.
Since PCl₃ is trigonal pyramidal and NH₄⁺ is tetrahedral, they have different geometries.

Option B: BeCl₂ and H₂O

BeCl₂ (Beryllium chloride): Beryllium forms two bonds with chlorine atoms and has no lone pairs. The molecular geometry is linear.
H₂O (Water): Oxygen forms two bonds with hydrogen atoms and has two lone pairs. The molecular geometry is bent (or V-shaped).
Since BeCl₂ is linear and H₂O is bent, they have different geometries.

Option C: CH₄ and CCl₄

CH₄ (Methane): Carbon forms four bonds with hydrogen atoms and has no lone pairs. The molecular geometry is tetrahedral.
CCl₄ (Carbon tetrachloride): Carbon forms four bonds with chlorine atoms and has no lone pairs. The molecular geometry is also tetrahedral.
Since both CH₄ and CCl₄ have a tetrahedral geometry, this pair has similar geometries.

Option D: IF₅ and PF₅

IF₅ (Iodine pentafluoride): Iodine forms five bonds with fluorine atoms and has one lone pair. The molecular geometry is square pyramidal.
PF₅ (Phosphorus pentafluoride): Phosphorus forms five bonds with fluorine atoms and has no lone pairs. The molecular geometry is trigonal bipyramidal.
Since IF₅ is square pyramidal and PF₅ is trigonal bipyramidal, they have different geometries.

Correct answer: C. CH₄, CCl₄