A diatomic molecule is made of two masses m1 and m2 which are separated by a distance r.  If we calculate its rotational energy by applying Bohr's rule of angular momentum quantization, its energy will be given by (n is an integer):

(1) m1+m22n2h22m12m22r2                   (2) n2h22π2(m1+m2)r2

(3) 2n2h2(m1+m2)r2                           (4) m1+m2n2h28π2m1m2r2

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Bohr's model of atom
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In a hydrogen atom, which of the following electronic transitions would involve the maximum energy change ?

(A) From n = 2 to n = 1

(B) From n = 3 to n = 1

(C) From n = 4 to n = 2

(D) From  n = 3 to n = 2

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Bohr's model of atom
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In the Bohr's hydrogen atom model, the radius of the stationary orbit is directly proportional to (n = principal quantum number) [CBSE PMT 1996; AIIMS 199; DCE 2002; AMU (med.) 2010)

(1) n-1        (2) n            (3) n-2         (4) n2

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Bohr's model of atom
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The Bohr model of atoms [2004]

(1) assumes that the angular momentum of electrons is quantised

(2) uses Einstein's photoelectric equation

(3) Predicts continuous emission spectra for atoms

(4) Predicts the same emission spectra for all types of atoms

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Bohr's model of atom
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When a hydrogen atom is raised from the ground state to excited state

(1) both KE and PE increase

(2) both KE and PE decrease

(3) PE increases and KE decreases

(4) PE decreases and KE increases

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Bohr's model of atom
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The extreme wavelengths of Paschen series are

(1) 0.365 μm and 0.565 μm

(2) 0.818 μm and 0.189 μm

(3) 1.45 μm and 4.04 μm

(4) 2.27 μm and 7.43 μm

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Spectral series
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A hydrogen atom is in an excited state of principal quantum number (n), it emits a photon of wavelength (λ) when it returns to the ground state. The value of n is 

(1) λRλR-1                   (2) (λR-1)λR

(3) λ(R-1)                   (4) None of these

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Bohr's model of atom
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 Consider an electron in the nth orbit of a hydrogen atom in the Bohr model. The circumference of the orbit can be expressed in terms of the de-Broglie wavelength λ of that electron as:

(1) (0.529) nλ           (2) nλ             (3) (13.6) λ         (4) nλ

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Bohr's model of atom
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In the Bohr's model of a hydrogen atom, the centripetal force is furnished by the Coulomb attraction between the proton and the electron.  If α0 is the radius of the ground state orbit, m is the mass and e is the charge on the electron, ε0 is the vaccum permittivity, the speed of the electron is  [1998]

(1) zero          (2) eε0a0m           (3) e4πε0a0m               (4) 4πε0a0me

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Bohr's model of atom
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The ground state energy of H-atom is 13.6 eV. The energy needed to ionise H-atom from its second excited state [1991]

(1) 1.51 eV          (2) 3.4 eV            (3) 13.6 eV             (4) 12.1 eV

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Bohr's model of atom
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