Keywords:#according to shape#JEE Main 2026 Evening Q62#Chemical Bonding and Molecular Structure JEE Main 2026#VSEPR Theory And Molecular Geometry JEE Main 2026
More Chemical Bonding and Molecular Structure Previous-Year Questions
Q64jee_main_2026_21_jan_morningVSEPR Theory
Given below are two statements:
Statement I: The number of species among mathrmSF_4$\mathrm{SF}_4$, mathrmNH_4^+$\mathrm{NH}_4^+$, [mathrmNiCl_4]^2-$[\mathrm{NiCl}_4]^{2-}$, mathrmXeF_4$\mathrm{XeF}_4$, [mathrmPtCl_4]^2-$[\mathrm{PtCl}_4]^{2-}$, mathrmSeF_4$\mathrm{SeF}_4$ and [mathrmNi(CN)_4]^2-$[\mathrm{Ni(CN)}_4]^{2-}$, that have tetrahedral geometry is 3.
Statement II: In the set [NO_2, BeH_2, BF_3, AlCl_3]$[NO_{2}, BeH_{2}, BF_{3}, AlCl_{3}]$, all the molecules have incomplete octet around central atom.
In the light of the above statements, choose the correct answer from the options given below:
A.textStatement I is true but Statement II is false$\text{Statement I is true but Statement II is false}$
B.textBoth Statement I and Statement II are false$\text{Both Statement I and Statement II are false}$
C.textStatement I is false but Statement II is true$\text{Statement I is false but Statement II is true}$
D.textBoth Statement I and Statement II are true$\text{Both Statement I and Statement II are true}$
Solution
### Core Logic
Evaluating Statement I:
- mathrmSF_4$\mathrm{SF}_4$: sp^3d$sp^3d$ (1 lone pair) rightarrow$\rightarrow$ See-saw
- mathrmXeF_4$\mathrm{XeF}_4$: sp^3d^2$sp^3d^2$ (2 lone pairs) rightarrow$\rightarrow$ Square planar
- [mathrmPtCl_4]^2-$[\mathrm{PtCl}_4]^{2-}$: dsp^2$dsp^2$rightarrow$\rightarrow$ Square planar
- [mathrmNiCl_4]^2-$[\mathrm{NiCl}_4]^{2-}$: sp^3$sp^3$rightarrow$\rightarrow$ Tetrahedral
- [mathrmNi(CN)_4]^2-$[\mathrm{Ni(CN)}_4]^{2-}$: dsp^2$dsp^2$rightarrow$\rightarrow$ Square planar
- mathrmSeF_4$\mathrm{SeF}_4$: sp^3d$sp^3d$ (1 lone pair) rightarrow$\rightarrow$ See-saw
- mathrmNH_4^+$\mathrm{NH}_4^+$: sp^3$sp^3$ (0 lone pairs) rightarrow$\rightarrow$ Tetrahedral
Total tetrahedral species = 2 ([mathrmNiCl_4]^2-$[\mathrm{NiCl}_4]^{2-}$ and mathrmNH_4^+$\mathrm{NH}_4^+$). Statement I says 3, so it is false.
Evaluating Statement II:
- NO_2$NO_2$: Central N has 7 valence electrons (odd-electron molecule, incomplete octet).
- BeH_2$BeH_2$: Central Be has 4 electrons (incomplete octet).
- BF_3$BF_3$: Central B has 6 electrons (incomplete octet).
- AlCl_3$AlCl_3$ (monomer): Central Al has 6 electrons (incomplete octet).
Therefore, all molecules have incomplete octets. Statement II is true.
### Step 1: Final Conclusion
Statement I is false, Statement II is true.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Chemical Bonding and Molecular Structure
Class 12 Chemistry: Coordination Compounds
Q64jee_main_2026_21_jan_eveningBond Length Trends
The correct increasing order of textC-H (A)$\text{C-H (A)}$, textC-O (B)$\text{C-O (B)}$, textC=O (C)$\text{C=O (C)}$ and textCequivtextN (D)$\text{C}\equiv\text{N (D)}$ bonds in terms of covalent bond length is:
(1) A < B < C < D$A < B < C < D$
(2) A < D < C < B$A < D < C < B$
(3) D < C < B < A$D < C < B < A$
(4) D < C < A < B$D < C < A < B$
A.(1) \ A < B < C < D$(1) \ A < B < C < D$
B.(2) \ A < D < C < B$(2) \ A < D < C < B$
C.(3) \ D < C < B < A$(3) \ D < C < B < A$
D.(4) \ D < C < A < B$(4) \ D < C < A < B$
Solution
### Core Logic
Comparing bond lengths:
- C–H (A): sim 107 text pm$\sim 107 \text{ pm}$
- C≡N (D): sim 116 text pm$\sim 116 \text{ pm}$
- C=O (C): sim 121 text pm$\sim 121 \text{ pm}$
- C–O (B): sim 143 text pm$\sim 143 \text{ pm}$
### Step 1: Final Conclusion
Thus, the increasing order is A < D < C < B$A < D < C < B$, corresponding to option (2).
### Pattern Recognition
Sees: covalent bond length comparison across bond orders and atomic radii.
Trap: Assuming triple bonds are always longer or shorter without accounting for smaller atomic radii like hydrogen.
### Chapter Mix
Class 11 Chemistry: Chemical Bonding and Molecular Structure
Q69jee_main_2026_21_jan_eveningBond Dissociation Enthalpy and Fajan's Rules
Given below are two statements:
Statement I: The correct order in terms of bond dissociation enthalpy is textCl_2 > textBr_2 > textF_2 > textI_2$\text{Cl}_2 > \text{Br}_2 > \text{F}_2 > \text{I}_2$.
Statement II: The correct trend in the covalent character of the metal halides is [textSnCl_4 > textSnCl_2]$[\text{SnCl}_4 > \text{SnCl}_2]$, [textPbCl_4 > textPbCl_2]$[\text{PbCl}_4 > \text{PbCl}_2]$ and [textUF_4 > textUF_6]$[\text{UF}_4 > \text{UF}_6]$ (or similar Fajan's rule trend).
In the light of the above statements, choose the correct answer from the options given below:
A.(1) text Statement I is true but Statement II is false$(1) \text{ Statement I is true but Statement II is false}$
B.(2) text Both Statement I and Statement II are true$(2) \text{ Both Statement I and Statement II are true}$
C.(3) text Statement I is false but Statement II is true$(3) \text{ Statement I is false but Statement II is true}$
D.(4) text Both Statement I and Statement II are false$(4) \text{ Both Statement I and Statement II are false}$
Solution
### Core Logic
- Statement I: Bond dissociation energy order for halogens is textCl_2 > textBr_2 > textF_2 > textI_2$\text{Cl}_2 > \text{Br}_2 > \text{F}_2 > \text{I}_2$ due to small size and lone-pair repulsions in fluorine weakening its bond. Statement I is true.
- Statement II: According to Fajan's rules, higher charge on cation increases covalent character, so textUF_6 > textUF_4$\text{UF}_6 > \text{UF}_4$ (higher oxidation state has greater covalent character), making the statement II claim regarding textUF_4 > textUF_6$\text{UF}_4 > \text{UF}_6$ false.
### Step 1: Final Conclusion
Statement I is true but Statement II is false, corresponding to option (1).
### Pattern Recognition
Sees: halogen bond dissociation energy anomalies and Fajan's rules for covalent character.
Trap: Assuming fluorine has the highest bond dissociation energy among halogens.
### Chapter Mix
Class 11 Chemistry: Chemical Bonding and Molecular Structure
Q52jee_main_2026_22_january_morningLewis Structures and Formal Charge
The formal changes on the atoms marked as (1) to (4) in the Lewis representation of HNO_3$HNO_{3}$ molecule respectively are
The image shows the Lewis structure of HNO3 with four atoms numbered 1 through 4.
A.text+1, 0, 0, -1$\text{+1, 0, 0, -1}$
B.text0, -1, 0, +1$\text{0, -1, 0, +1}$
C.text0, +1, 0, -1$\text{0, +1, 0, -1}$
D.text0, 0, -1, +1$\text{0, 0, -1, +1}$
Solution
### Related Formula
textFormal charge = (textValence e^-) - (textNon-bonding e^-) - fractextBonding e^-2$$\text{Formal charge} = (\text{Valence } e^{-}) - (\text{Non-bonding } e^{-}) - \frac{\text{Bonding } e^{-}}{2}$$
### Core Logic
Evaluate the structure of HNO_3$HNO_{3}$ shown in the solution image:
The image shows the Lewis structure of HNO3 with four atoms numbered 1 through 4.
Atom 1 (Oxygen with H and N):
F.C. = 6 - 4 - frac42 = 0$F.C. = 6 - 4 - \frac{4}{2} = 0$
Atom 2 (Nitrogen):
F.C. = 5 - 0 - frac82 = +1$F.C. = 5 - 0 - \frac{8}{2} = +1$
Atom 3 (Double bonded Oxygen):
F.C. = 6 - 4 - frac42 = 0$F.C. = 6 - 4 - \frac{4}{2} = 0$
Atom 4 (Single bonded Oxygen):
F.C. = 6 - 6 - frac22 = -1$F.C. = 6 - 6 - \frac{2}{2} = -1$
### Step 1: Final Conclusion
The formal charges on atoms (1), (2), (3), and (4) are respectively 0, +1, 0, -1.
### Pattern Recognition
In nitro groups (-NO_2$-NO_2$), the central nitrogen is always +1, the single bonded oxygen is -1, and the double-bonded oxygen is 0.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Chemical Bonding and Molecular Structure
Q68jee_main_2026_22_january_morningHybridization and VSEPR Theory
Two p-block elements X and Y form fluroides of the type EF_3$EF_{3}$. The fluoride compound XF_3$XF_{3}$ is a Lewis acid and YF_3$YF_{3}$ is a Lewis base. The hybridization of the central atoms of XF_3$XF_{3}$ and YF_3$YF_{3}$ respectively are
A.textBoth sp^3$\text{Both } sp^{3}$
B.sp^2 text and sp^3$sp^{2} \text{ and } sp^{3}$
C.sp^3 text and sp^2$sp^{3} \text{ and } sp^{2}$
D.textBoth sp^2$\text{Both } sp^{2}$
Solution
### Core Logic
XF_3$XF_3$ acts as a Lewis acid, meaning it is an electron-deficient species capable of accepting an electron pair. A common example from the p-block is BF_3$BF_3$. The central Boron atom has 3 bond pairs and 0 lone pairs. Therefore, its steric number is 3, corresponding to sp^2$sp^2$ hybridization.
YF_3$YF_3$ acts as a Lewis base, meaning it has an available lone pair to donate. A common example is NF_3$NF_3$. The central Nitrogen atom has 3 bond pairs and 1 lone pair. Its steric number is 4, corresponding to sp^3$sp^3$ hybridization.
### Step 1: Final Conclusion
The hybridization of X and Y respectively are sp^2$sp^2$ and sp^3$sp^3$.
### Pattern Recognition
Electron deficient central atoms (Group 13) form sp^2$sp^2$ planar molecules. Atoms with a lone pair (Group 15) form sp^3$sp^3$ pyramidal molecules.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Chemistry: Chemical Bonding and Molecular Structure
Class 11 Chemistry: p-Block Elements
More Chemical Bonding and Molecular Structure Questions — jee_main_2026_28_january_evening
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