The valence electron in alkali metal is a [1990]

(1) f-electron       (2) p-electron         (3) s-electron         (4) d-electron

Concept Questions :-

Various atomic model
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Light is a kind of wave. The wavelength of visible light ranges from about 4000 A to 7000 A. Which of the following statements is false?

1. Ultraviolet light has a wavelength shorter than 4000 A

2. Infrared light has a wavelength longer than 7000 A

3. Red light has wavelength near about 7000 A

4. Violet light has wavelength near about 7000 A.

Concept Questions :-

Spectral series
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An α-particle of energy 5 MeV is scattered through 180° by a fixed uranium nucleus. The distance of closest approach is of the order

(1) 10-10 m           (2) 10-13 m            (3) 10-14 m             (4) 10-16 m

Concept Questions :-

Various atomic model
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Out of the following which one is not a possible energy for a photon to be emitted by hydrogen atom according to Bohr's atomic model:

(1) 13.6 eV             (2) 0.65 eV              (3) 1.9 eV              (4) 11.1 eV

Concept Questions :-

Bohr's model of atom
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Energy of an electron in an excited hydrogen atom is -3.4 eV. Its angular momentum will be (h = 6.626 × 10-34 J-s)

1. 1.11 × 1034 J s                   2. 1.51 ×10-31 J s

3. 2.11 × 10-34 J s                  4. 3.72 × 10-34 J s

 

Concept Questions :-

Bohr's model of atom
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As per Bohr model, the minimum energy (in eV) required to remove the electron from the ground state of double ionized lithium (Z=3) is 

(1) 1.51        (2) 13.6            (3) 40.8        (4) 122.4

Concept Questions :-

Bohr's model of atom
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The wavelength of Ka X-rays produced by an X-ray tube is 0.76 A. Find the atomic number of the anode material of the tube?

1. 41                                    2. 30

3. 20                                    4. 10

Concept Questions :-

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According to Bohr's theory the moment of momentum of an electron revolving in second orbit of hydrogen atom will be [MP PET 1999; KCET 2003; VITEEE 2006]

(1) 2πh        (2) πh         (3) hπ          (4) 2hπ

Concept Questions :-

Bohr's model of atom
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The ionisation energy of hydrogen atom is 13.6 eV. Following Bohr's theory, the energy corresponging to a transition between 3rd and 4th orbit is   [1992]

(1) 3.40 eV        (2) 1.51 eV        (3) 0.85        (4) 0.66 eV

Concept Questions :-

Bohr's model of atom
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The K line obtained for molybdenum (Z = 42) target is 0.71 A. Then, the wavelength of the Kα line of copper (Z = 29) is:

(A) 2.14 A                               (B) 1.52 A

(C) 1.04 A                               (D) 0.71 A

Concept Questions :-

Spectral series
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