Bohr's Model for Hydrogen Atom — NEET Chemistry MCQs with Solutions
Free NEET Chemistry Bohr's Model for Hydrogen Atom MCQs with step-by-step solutions (30 questions). Part of Atomic Structure. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Bohr's Model for Hydrogen Atom · easy · theory
According to Bohr's model, an electron revolves around the nucleus only in certain allowed orbits in which it:
A. Moves in a straight line
B. Continuously radiates energy
C. Does not radiate energy (stationary states) ✓ Correct
D. Continuously absorbs energy
Solution: Bohr postulated that electrons occupy fixed "stationary" orbits of definite energy and do not radiate energy while in them.
Q2 — Bohr's Model for Hydrogen Atom · medium · theory
According to Bohr, the angular momentum of an electron in an allowed orbit is quantised as:
A. mvr = nh/2π ✓ Correct
B. mvr = 2πnh
C. mvr = h/2πn
D. mvr = nh
Solution: Bohr's quantisation condition: the angular momentum mvr equals n(h/2π), where n = 1, 2, 3, ….
Q3 — Bohr's Model for Hydrogen Atom · easy · numerical
The radius of the first Bohr orbit of the hydrogen atom is about:
A. 5.29 Å
B. 0.529 Å ✓ Correct
C. 0.0529 Å
D. 52.9 Å
Solution: The first Bohr orbit (Bohr radius) of hydrogen is 0.529 Å (52.9 pm).
Q4 — Bohr's Model for Hydrogen Atom · medium · numerical
The radius of the second orbit of the hydrogen atom is (Bohr radius = 0.529 Å):
A. 1.06 Å
B. 4.76 Å
C. 2.12 Å ✓ Correct
D. 0.529 Å
Solution: rₙ = 0.529 n² Å (for H). For n = 2: r = 0.529 × 4 = 2.12 Å.
Q5 — Bohr's Model for Hydrogen Atom · medium · theory
The radius of a Bohr orbit in the hydrogen atom is directly proportional to:
A. n
B. 1/n²
C. n² ✓ Correct
D. 1/n
Solution: rₙ = 0.529 n²/Z Å, so for a given atom the radius is proportional to n².
Q6 — Bohr's Model for Hydrogen Atom · easy · theory
The energy of an electron in the nth orbit of the hydrogen atom is given by:
A. $E_n = -13.6\,n^2$ eV
B. $E_n = -\dfrac{13.6}{n}$ eV
C. $E_n = -\dfrac{13.6}{n^2}$ eV ✓ Correct
D. $E_n = +\dfrac{13.6}{n^2}$ eV
Solution: For hydrogen, Eₙ = −13.6/n² eV (negative because the electron is bound).
Q7 — Bohr's Model for Hydrogen Atom · easy · numerical
The energy of the electron in the ground state (n = 1) of the hydrogen atom is:
A. 0 eV
B. −1.51 eV
C. −3.4 eV
D. −13.6 eV ✓ Correct
Solution: E₁ = −13.6/1² = −13.6 eV, the lowest (most negative, most stable) energy.
Q8 — Bohr's Model for Hydrogen Atom · medium · numerical
The energy of the electron in the second orbit (n = 2) of the hydrogen atom is:
A. −6.8 eV
B. −13.6 eV
C. −3.4 eV ✓ Correct
D. −1.51 eV
Solution: E₂ = −13.6/2² = −13.6/4 = −3.4 eV.
Q9 — Bohr's Model for Hydrogen Atom · medium · numerical
The energy of the electron in the third orbit (n = 3) of hydrogen is approximately:
A. −4.53 eV
B. −3.4 eV
C. −0.85 eV
D. −1.51 eV ✓ Correct
Solution: E₃ = −13.6/3² = −13.6/9 ≈ −1.51 eV.
Q10 — Bohr's Model for Hydrogen Atom · medium · numerical
The ionisation energy of the hydrogen atom (from its ground state) is:
A. 3.4 eV
B. 13.6 eV ✓ Correct
C. 10.2 eV
D. 27.2 eV
Solution: Ionisation energy = E∞ − E₁ = 0 − (−13.6) = 13.6 eV, the energy to remove the electron from n = 1 to n = ∞.
Q11 — Bohr's Model for Hydrogen Atom · medium · numerical
The energy required to excite the electron in a hydrogen atom from n = 1 to n = 2 is:
A. 1.9 eV
B. 3.4 eV
C. 10.2 eV ✓ Correct
D. 13.6 eV
Solution: ΔE = E₂ − E₁ = (−3.4) − (−13.6) = 10.2 eV.
Q12 — Bohr's Model for Hydrogen Atom · medium · theory
The negative sign in the expression for the energy of an electron in a Bohr orbit indicates that:
A. The electron has negative mass
B. The electron is bound to the nucleus ✓ Correct
C. The electron repels the nucleus
D. The energy is imaginary
Solution: The negative sign means the electron in the atom has lower energy than a free electron (taken as zero) — it is bound to the nucleus.
Q13 — Bohr's Model for Hydrogen Atom · medium · theory
According to Bohr, radiation is emitted when an electron:
A. Stays in the same orbit
B. Leaves the atom completely
C. Jumps from a higher orbit to a lower orbit ✓ Correct
D. Jumps from a lower orbit to a higher orbit
Solution: Light of energy ΔE = hν is emitted when the electron falls from a higher-energy orbit to a lower-energy one.
Q14 — Bohr's Model for Hydrogen Atom · medium · theory
The Rydberg formula for the wavenumber of a spectral line of hydrogen is:
A. $\bar{\nu} = R\left(\dfrac{1}{n_1} - \dfrac{1}{n_2}\right)$
B. $\bar{\nu} = R\left(n_1^2 - n_2^2\right)$
C. $\bar{\nu} = R\left(\dfrac{1}{n_2^2} - \dfrac{1}{n_1^2}\right)$
D. $\bar{\nu} = R\left(\dfrac{1}{n_1^2} - \dfrac{1}{n_2^2}\right)$ ✓ Correct
Solution: For emission, ν̄ = 1/λ = R(1/n₁² − 1/n₂²) with n₂ > n₁ and R = 1.097 × 10⁷ m⁻¹.
Q15 — Bohr's Model for Hydrogen Atom · easy · theory
The Lyman series of the hydrogen spectrum lies in the:
A. Infrared region
B. Microwave region
C. Visible region
D. Ultraviolet region ✓ Correct
Solution: The Lyman series (transitions to n = 1) lies in the ultraviolet region.
Q16 — Bohr's Model for Hydrogen Atom · easy · theory
The Balmer series of the hydrogen spectrum lies in the:
A. Ultraviolet region
B. X-ray region
C. Infrared region
D. Visible region ✓ Correct
Solution: The Balmer series (transitions to n = 2) lies in the visible region of the spectrum.
Q17 — Bohr's Model for Hydrogen Atom · medium · theory
The Paschen series of the hydrogen spectrum lies in the:
A. Ultraviolet region
B. Infrared region ✓ Correct
C. Microwave region
D. Visible region
Solution: The Paschen series (transitions to n = 3) lies in the infrared region.
Q18 — Bohr's Model for Hydrogen Atom · medium · theory
The spectral lines of the Balmer series arise from electronic transitions ending at:
A. n = 3
B. n = 1
C. n = 2 ✓ Correct
D. n = 4
Solution: All Balmer lines correspond to electrons falling from higher levels (n ≥ 3) down to n = 2.
Q19 — Bohr's Model for Hydrogen Atom · medium · theory
The Lyman series arises from electronic transitions ending at:
A. n = 2
B. n = 1 ✓ Correct
C. n = 5
D. n = 3
Solution: Lyman lines correspond to transitions from higher levels down to the ground state, n = 1.
Q20 — Bohr's Model for Hydrogen Atom · medium · theory
The Pfund series of the hydrogen spectrum corresponds to transitions ending at:
A. n = 4
B. n = 2
C. n = 5 ✓ Correct
D. n = 3
Solution: The Pfund series (in the far infrared) consists of transitions from higher levels down to n = 5.
Q21 — Bohr's Model for Hydrogen Atom · medium · numerical
When an electron in a hydrogen atom falls from n = 4 to n = 1, the maximum number of spectral lines that can appear is:
A. 4
B. 6 ✓ Correct
C. 3
D. 10
Solution: Number of lines = n(n − 1)/2 = 4 × 3/2 = 6.
Q22 — Bohr's Model for Hydrogen Atom · medium · theory
In the Lyman series, the spectral line of longest wavelength corresponds to the transition:
A. n = 3 → n = 1
B. n = 3 → n = 2
C. n = 2 → n = 1 ✓ Correct
D. n = ∞ → n = 1
Solution: Longest wavelength = smallest energy gap. Within the Lyman series the smallest gap is n = 2 → 1.
Q23 — Bohr's Model for Hydrogen Atom · medium · theory
In Bohr's model, the velocity of the electron in the nth orbit is proportional to:
A. Z n
B. n²
C. Z/n ✓ Correct
D. n/Z
Solution: vₙ = 2.18 × 10⁶ (Z/n) m/s, so the velocity is proportional to Z/n and decreases as n increases.
Q24 — Bohr's Model for Hydrogen Atom · medium · theory
As the value of n increases, the energy of the electron in a hydrogen atom:
A. Increases (becomes less negative) ✓ Correct
B. Becomes zero immediately
C. Decreases (becomes more negative)
D. Remains constant
Solution: Eₙ = −13.6/n² eV; as n increases the value gets closer to zero, i.e. the energy increases (less negative).
Q25 — Bohr's Model for Hydrogen Atom · medium · numerical
The energy of the electron in the ground state of the He⁺ ion (Z = 2) is:
A. −54.4 eV ✓ Correct
B. −13.6 eV
C. −27.2 eV
D. −6.8 eV
Solution: Eₙ = −13.6 Z²/n² eV. For He⁺, n = 1, Z = 2: E = −13.6 × 4 = −54.4 eV.
Q26 — Bohr's Model for Hydrogen Atom · medium · numerical
The radius of the first orbit of the He⁺ ion (Z = 2) is (Bohr radius = 0.529 Å):
A. 2.116 Å
B. 1.058 Å
C. 0.264 Å ✓ Correct
D. 0.529 Å
Solution: rₙ = 0.529 n²/Z Å. For He⁺, n = 1, Z = 2: r = 0.529/2 ≈ 0.264 Å.
Q27 — Bohr's Model for Hydrogen Atom · medium · theory
Bohr's model successfully explains the spectrum of:
A. Hydrogen and hydrogen-like species (He⁺, Li²⁺) ✓ Correct
B. Only molecules
C. All multi-electron atoms
D. Only helium atoms
Solution: Bohr's model works for one-electron systems: H, He⁺, Li²⁺, Be³⁺, etc.
Q28 — Bohr's Model for Hydrogen Atom · easy · theory
A major limitation of Bohr's model is that it fails to explain the spectra of:
A. The Li²⁺ ion
B. Atoms containing more than one electron ✓ Correct
C. The hydrogen atom
D. The He⁺ ion
Solution: Bohr's model cannot account for the spectra of multi-electron atoms, where electron–electron interactions matter.
Q29 — Bohr's Model for Hydrogen Atom · medium · theory
Bohr's model could NOT explain the splitting of spectral lines observed in a magnetic field, known as the:
A. Photoelectric effect
B. Tyndall effect
C. Zeeman effect ✓ Correct
D. Compton effect
Solution: The splitting of spectral lines in a magnetic field (Zeeman effect) — and in an electric field (Stark effect) — could not be explained by Bohr's model.
Q30 — Bohr's Model for Hydrogen Atom · medium · theory
Bohr's model is inconsistent with which later principle, since it assigns the electron both a fixed orbit (position) and a definite momentum?
A. Aufbau principle
B. Heisenberg's uncertainty principle ✓ Correct
C. Hund's rule
D. Pauli's exclusion principle
Solution: Fixed, well-defined orbits violate Heisenberg's uncertainty principle, which forbids knowing an electron's exact position and momentum simultaneously.