In the below reaction, geometry of BCl3, X respectively are
1
Pyramidal, tetrahedral
2
Pyramidal, octahedral
3
Trigonal planar, tetrahedral
4
Trigonal planar, octahedral
Official Solution
Correct Option: (3)
To determine the molecular geometry of BCl3 and the product X in the provided reaction, we need to consider the VSEPR (Valence Shell Electron Pair Repulsion) theory. This theory helps predict the geometry of molecules based on minimizing the repulsion between electron pairs around a central atom.
Step 1: Determine the geometry of BCl3. Boron is the central atom in BCl3 and has three valence electrons. Chlorine has seven valence electrons and forms a single bond with boron, using one of boron's valence electrons. Since BCl3 has three bond pairs and no lone electron pairs on the boron atom, it adopts a trigonal planar geometry to minimize electron pair repulsion.
Step 2: Predict the geometry of the species X. In the reaction BCl3 + NH3, NH3 donates its lone pair to form a coordinate bond with BCl3. Through this process, a tetrahedral geometry is formed around the boron atom in the adduct, as there are now four regions of electron density (three from B-Cl bonds and one from N-B coordinate bond).
Therefore, the geometry of BCl3 is trigonal planar, and the geometry of the compound X (formed after the reaction with NH3) is tetrahedral.
Correct Answer: Trigonal planar, tetrahedral
02
PYQ 2023
medium
chemistryID: ap-eapce
Match the following
1
A-III, B-IV, C-I, D-II
2
A-I, B-II, C-IV, D-III
3
A-II, B-I, C-III, D-IV
4
A-III, B-IV, C-II, D-I
Official Solution
Correct Option: (1)
- **A) XeF **: Xenon difluoride (XeF ) has 3 lone pairs on the central Xenon atom, thus it matches with **III**. - **B) XeO **: Xenon trioxide (XeO ) has 0 lone pairs on the central Xenon atom, hence it corresponds with **IV**. - **C) XeF **: Xenon tetrafluoride (XeF ) has 2 lone pairs on the central Xenon atom, matching with **I**. - **D) PF **: PF has 1 lone pair on the central atom (Phosphorus), so it corresponds with **II**.
03
PYQ 2025
medium
chemistryID: ap-eapce
Match the following molecules with their bond angles:
Observe the following molecules:
.
The number of molecules with the same geometry as that of is:
1
6
2
5
3
4
4
3
Official Solution
Correct Option: (2)
has a bent or V-shaped geometry due to lone pair on Sn. Count molecules with similar bent geometry: - : bent - : bent - : bent - : bent - : bent Other molecules like , , have linear or different geometries. Total = 5 molecules.
