Atoms and Electrons – Exercise – 1

1. In general, a shell contains a maximum of …………. electrons.

(a)  2n
(b)  2n2
(c)  2n–1
(d)  2n+1

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
2. Emission of a beta particle from an atom :

(a)  increases the number of protons in an atom
(b)  increases the number of neutrons in an atom
(c)  decreases the number of protons in an atom
(d)  decreases the number of neutrons in an atom

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
3. If an atom has an atomic number of 6, then it has :

(a)  3 electrons & 3 protons
(b)  4 electrons & 2 protons
(c)  2 electrons & 4 protons
(d)  6 electrons & 6 protons

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
4. An excited electron in an atom returns to the ground state :

(a)  always in one jump
(b)  in one or more jumps
(c)  always in two jumps
(d)  always in three jumps

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
5. The maximum number of electron that an M-shell of an atom can contain is :

(a)  4
(b)  12
(c)  18
(d)  34

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
6. In Bohr’s theory of atom, all the orbits of the electrons are considered circular in shape. The de Broglie wavelength λn corresponding to the electron in the nth orbit is :

(a)  proportional to n
(b)  proportional to n2
(c)  inversely proportional to n
(d)  inversely proportional to n2

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
7. When an electron moves from a higher orbit to a lower orbit :

(a)  emission of energy takes place
(b)  absorption of energy takes place
(c)  size of the atom increases
(d)  either absorption or emission of energy takes place

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
8. Based on Quantum mechanical theory, the mass of holes are …………. than the electrons.

(a)  larger
(b)  smaller
(c)  equal
(d)  none of the above

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
9. The nucleus of atom is made of :

(a)  protons & electrons
(b)  protons & neutrons
(c)  protons & krypton
(d)  neutron & electrons

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
10. The forbidden charge in germanium at 0°K is :

(a)  1.21 eV
(b)  1.00 eV
(c)  0.01 eV
(d)  0.00 eV

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
11. One electron volt equals to :

(a)  01.60 × 10^–19
(b)  09.11 × 10^–31
(c)  19.40 × 10^-10
(d)  01.16 × 10^–19

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
12. In germanium the majority of electrons are :

(a)  1.22 m^2/Vs
(b)  1.44 m^2/Vs
(c)  1.66 m^2/Vs
(d)  1.88 m^2/Vs

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
13. Which one of the following pair is correctly matched ?

(a)  Mass spectroscopy – Chadwick
(b)  Atomic number – Moseley
(c)  Neutron – Millikan
(d)  Measurement of charge of an electron – Aston

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
14. Impact ionization is a process of liberation of free electrons by breaking :

(a)  Metallic bond
(b)  Ionic bond
(c)  Covalent bond
(d)  van der Waals bond

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
15. The atomic number of silicon is :

(a)  14
(b)  16
(c)  18
(d)  12

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
16. Which type of the following structures contains two atoms per cell ?

(a)  Body centered cubic
(b)  Face centered cubic
(c)  Single cubic cell
(d)  None of the above

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
17. In silicon material, the mobility of free electron is :

(a)  2.5 m^2/Vs
(b)  2.7 m^2/Vs
(c)  1.66 m^2/Vs
(d)  2.33 m^2/Vs

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
18. A Nixie cold cathode glow discharge tube has :

(a)  20 cathodes
(b)  15 cathodes
(c)  14 cathodes
(d)  10 cathodes

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
19. The minority holes are about ………. that of electron.

(a)  Half
(b)  Same
(c)  Twice
(d)  Thrice

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
20. The volume charge density of mobile carriers is expressed in :

(a)  Coulombs / cubic meters
(b)  Coulombs / meters
(c)  Coulombs / seconds
(d)  Coulombs / volts

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
21. Valence electrons are :

(a)  In the closest orbit of the nucleus
(b)  In the most distant orbit from the nucleus
(c)  In the various orbits around the nucleus
(d)  Not associated with a particular atom

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
22. In a Silicon crystal, the number of covalent bonds a single atom can form is :

(a)  2
(b)  4
(c)  6
(d)  8

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
23. Consider the following statements regarding Bohr atomic model.(Pick the right one)1. It introduces the idea of stationary orbit.2. It assumes that angular momentum of electron is equal to ½(h/2π).3. It uses planetary model of atom revolving in circular orbit.

(a)  1 & 2
(b)  2 & 3
(c)  1 & 3
(d)  1, 2 & 3

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
24. Consider the following statements Rutherford’s alpha particle scattering experiment proved that the nucleus
1. Contains massive particles
2. Is a +ve charge center
3. Is quite stable
Which of the statements are correct ?

(a)  1, 2, 3
(b)  1, 2
(c)  2, 3
(d)  1, 3

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
25. The atomic number of germanium is :

(a)  24
(b)  26
(c)  28
(d)  32

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
26. The electron density in conduction band is proportional to :

(a)  Donor concentration
(b)  Square of donor concentration
(c)  Square root of donor concentration
(d)  Cube root of donor concentration

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
27. Which electron in an element is responsible for chemical & electrical properties ?

(a)  Valence electrons
(b)  Revolving electrons
(c)  Active electrons
(d)  Passive electrons

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
28. The absolute zero temperature is equal to :

(a)  0°C
(b)  273°C
(c)  –273°C
(d)  27°C

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
29. …….. number of electrons is responsible for its chemical and electrical properties.

(a)  32
(b)  14
(c)  16
(d)  9

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
30. An electron in a completely filled band :

(a)  Contributes to the flow of electric current
(b)  Does not contributes to the flow of electric current
(c)  Can move but doesn’t contribute to the flow of electric current
(d)  None of these

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
31. The relation between the energy released and frequency of the emitted radiation of an atom is given by the expression :

(a)  ΔE = h/f
(b)  ΔE = h + f
(c)  ΔE = h f
(d)  ΔE = 1 + h/f

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
32. The elements in a periodic table are arranged, based on the increasing order of :

(a)  Atomic number
(b)  Mass number
(c)  Molecular weight
(d)  Alphabetical order

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
33. The solid which has no periodic structures at all is called as :

(a)  Crystalline solid
(b)  Amorphous solid
(c)  Polycrystalline solid
(d)  Solids

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
34. Diffusion constant for electron is …….. to hole.

(a)  Equal
(b)  Greater than
(c)  Lesser than
(d)  Can’t be determined

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
35. The velocity of the electron in the nth orbit is given by the equation :

(a)  Vn= (hn/ πmrn)
(b)  Vn= (πh2/ mrn)
(c)  Vn= (n(h/2π)/ mrn)
(d)  Vn= (nh/2πmrn)

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
36. What is the de Broglie wavelength of neutrons at room temperature ?

(a)  0.145 nm
(b)  0.82 nm
(c)  0.64 nm
(d)  4.23 nm

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
37. Germanium has a :

(a)  Diamond cube (dc) structure
(b)  Simple cube (sc) structure
(c)  Face centered cube (fcc) structure
(d)  Body centered cube (bcc) structure

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
38. The electron mobility is greater in :

(a)  Germanium
(b)  Silicon
(c)  Gallium arsenide
(d)  Bakelite

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
39. The relative distance of the electron from the nucleus is same as :

(a)  The relative distance between Earth and Moon
(b)  The relative distance between Sun and Earth
(c)  The relative distance between Earth and Pluto
(d)  The relative distance between Sun and Pluto

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
40. One part of donor impurities to 108 parts of germanium :

(a)  Increases the conductivity of the crystal twofold
(b)  Increases the conductivity of the crystal fourfold
(c)  Increases the conductivity of the crystal eightfold
(d)  Increases the conductivity of the crystal tenfold

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
41. The Bragg’s diffraction equation is given by :

(a)  sin θ= nλ/ 2d
(b)  sin θ= n/2dλ
(c)  sin θ= 2dnλ
(d)  sin θ= 2(n–λd)

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
42. The donor impurity must have only ……. valence electrons.

(a)  2
(b)  3
(c)  4
(d)  5

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
43. The Miller indices of the diagonal plane of a cube are :

(a)  0 1 0
(b)  1 1 0
(c)  0 0 1
(d)  1 1 1

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
44. One angstrom is equal to :

(a)  10^–9 metre
(b)  10^–11 metre
(c)  10^–10 metre
(d)  10^–12 metre

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
45. Which one of the following materials does not have a covalent bond ?

(a)  Silver
(b)  Silicon
(c)  Organic polymer
(d)  Diamond

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
46. Mobility of electron is highest in :

(a)  Silicon
(b)  Germanium
(c)  Gallium arsenide
(d)  Carbon

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
47. The nature of atomic bond found in diamond is :

(a)  Tetravalent
(b)  Covalent
(c)  Metallic
(d)  Ionic

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
48. Facing fraction of simple cube is :

(a)  6.48
(b)  0.52
(c)  0.65
(d)  0.89

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
49. According to Coulomb’s first law :

(a)  Like charges attract each other
(b)  Like charges repel each other
(c)  There is no force between the charges
(d)  None of these

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
50. When an electron moves from lower orbit to a higher orbit :

(a)  Emission of energy takes place
(b)  Absorption of energy takes place
(c)  Size of atom increases
(d)  Either absorption or emission of energy takes place

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.