Atomic structure and chemical bonding are high-yield chapters for JEE Main and the base for most of physical and inorganic chemistry. This set covers the Bohr model, quantum numbers, electronic configurations and nodes, then moves to VSEPR shapes, hybridisation and molecular orbital theory.
How to practise: read each question and tap the option you think is correct. You will see right away whether you got it, along with a short explanation, and your score is tracked at the bottom of the screen. This set has 15 questions.
Topics covered in this set
- Bohr model: radius and energy
- Quantum numbers, orbitals and nodes
- Electronic configuration and exceptions
- de Broglie and Heisenberg principles
- VSEPR shapes and hybridisation
- MO theory, bond order and dipole moment
JEE Chemistry MCQs with answers and explanations
Q1. What is the maximum number of electrons that can occupy the shell with principal quantum number n = 3?
a) 32
b) 18
c) 8
d) 9
Q2. How many orbitals are there in the shell with n = 3?
a) 6
b) 18
c) 3
d) 9
Q3. What is the ground-state electronic configuration of chromium (Z = 24)?
a) [Ar] 3d⁵ 4s¹
b) [Ar] 4s² 4p⁴
c) [Ar] 3d⁶
d) [Ar] 3d⁴ 4s²
Q4. In the Bohr model of hydrogen, what is the ratio of the radius of the 3rd orbit to the 1st orbit?
a) 1 : 9
b) 9 : 1
c) 27 : 1
d) 3 : 1
Q5. The energy of the electron in the ground state of hydrogen is −13.6 eV. What is its energy in the n = 2 state?
a) −1.51 eV
b) −27.2 eV
c) −6.8 eV
d) −3.4 eV
Q6. How many radial nodes does a 3s orbital have?
a) 1
b) 2
c) 3
d) 0
Q7. The de Broglie wavelength of a particle of mass m moving with speed v is:
a) λ = hv / m
b) λ = h / m
c) λ = mv / h
d) λ = h / mv
Q8. Heisenberg's uncertainty principle is expressed as:
a) Δx + Δp ≥ h
b) Δx · Δp ≥ h / 4π
c) Δx · Δp = 0
d) Δx / Δp ≥ h / 2π
Q9. What is the hybridisation of each carbon atom in ethyne (HC≡CH)?
a) sp²
b) sp
c) dsp²
d) sp³
Q10. What is the shape of the ammonia (NH₃) molecule?
a) Tetrahedral
b) T-shaped
c) Trigonal planar
d) Trigonal pyramidal
Q11. What is the geometry and hybridisation of SF₆?
a) Octahedral, sp³d²
b) Trigonal bipyramidal, sp³d
c) Tetrahedral, sp³
d) Square planar, dsp²
Q12. According to molecular orbital theory, what are the bond order and magnetic nature of O₂?
a) Bond order 3, diamagnetic
b) Bond order 1, paramagnetic
c) Bond order 2, diamagnetic
d) Bond order 2, paramagnetic
Q13. What is the bond order of N₂?
a) 2.5
b) 3
c) 2
d) 1
Q14. Which of these molecules has zero dipole moment?
a) H₂O
b) CHCl₃
c) NH₃
d) CO₂
Q15. Which element has the highest electronegativity on the Pauling scale?
a) Nitrogen
b) Chlorine
c) Oxygen
d) Fluorine
Quick revision notes
- Shell capacity 2n², orbitals n²; radial nodes n − l − 1.
- Bohr: rₙ ∝ n²/Z, Eₙ = −13.6 Z²/n² eV.
- Exceptions: Cr 3d⁵4s¹, Cu 3d¹⁰4s¹.
- VSEPR: NH₃ pyramidal (≈107°), H₂O bent (≈104.5°), SF₆ octahedral.
- MO: O₂ bond order 2 and paramagnetic; N₂ bond order 3.
Frequently asked questions
Are these JEE previous year questions?
No, they are original practice questions written to the JEE Main syllabus and level.
Why is O₂ paramagnetic when its Lewis structure shows all electrons paired?
Molecular orbital theory places two electrons singly in two degenerate π* orbitals, which explains the observed paramagnetism.
How much of JEE Chemistry is from these chapters?
Atomic structure and bonding are asked regularly and also support thermodynamics, coordination compounds and organic reaction mechanisms.
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