Structure Of Atom
Class:9 | Chapter:4
Multiple Choice Questions
1. Maximum number of electrons that can be filled in the third orbit of an Atom is(a) 18
(b) 8
(c) 10
(d) 32
2. Valency of an element whose atomic number is 5,is
(a) 1
(b) 3
(c) 2
(d) 4
3. The particles present in the nucleus of an Atom are
(a) Proton and electron
(b) Electron and neutron
(c) Proton and neutron
(d) None of these
4. The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?
(a) 13
(b) 10
(c) 14
(d) 16
5. An atom with 11 protons and 12 neutrons will have a valency of
(a) 3
(b) 7
(c) 1
(d) 2
6. How many electrons are present in M-shell of an element with atomic number 19?
(a) 5
(b) 8
(c) 12
(d) 18
7. Which of the following isotope is used in the treatment of blood cancer?
(a) P-32
(b) I-131
(c) Co-60
(d) any of these
8. The electronic configuration of Sulphur is
(a) 2,7
(b) 2,8,8,6
(c) 2,8,6
(d) 2,7,8
9. The nucleons are
(a) Protons and electrons
(b) Neutrons and electrons
(c) Protons and neutrons
(d) None of these
10. The cathode ray experiment was done for the first time by:
(a) J.J. Thomson
(b) John Dalton
(c) Goldstein
(d) Rutherford
11. Which of the following correctly represents the electronic distribution in the Mg atom?
(a) 3, 8, 1
(b) 2, 8, 2
(c) 1, 8, 3
(d) 8, 2, 2
12. Rutherford’s ‘alpha (α) particles scattering experiment’ resulted in the discovery of
(a) electron
(b) proton
(c) nucleus in the atom
(d) atomic mass
13. Which of the following are true for an element?
(i) Atomic number = number of protons + number of electrons
(ii) Mass number = number of protons + number of neutrons
(iii) Atomic mass = number of protons = number of neutrons
(iv) Atomic number = number of protons = number of electrons
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (ii) and (iv)
14. Atomic models have been improved over the years. Arrange the following atomic models in the order of their chronological order
(i) Rutherford’s atomic model
(ii) Thomson’s atomic model
(ii) Bohr’s atomic model
(a) (i), (ii) and (iii)
(b) (ii), (iii) and (i)
(c) (ii), (i) and (iii)
(d) (iii), (ii) and (i)
15. The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?
(a) 13
(b) 10
(c) 14
(d) 16
16. The first model of an atom was given by
(a) N. Bohr
(b) E. Goldstein
(c) Rutherford
(d) J.J. Thomson
17. An atom with 3 protons and 4 neutrons will have a valency of
(a) 3
(b) 7
(c) 1
(d) 4
18. Which of the following statements about Rutherford’s model of atom are correct?
(i) Considered the nucleus as positively charged.
(ii) Established that the a-particles are four times as heavy as a hydrogen atom.
(iii) Can be compared to solar system.
(iv) Was in agreement with Thomson’s model.
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) only (i)
19. How many electrons are present in M-shell of an element with atomic number 20?
(a) 5
(b) 8
(c) 12
(d) 18
20. The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?
(a) 13
(b) 10
(c) 14
(d) 16
21. An alpha particle is also known as:
(a) subatomic particle
(b) an unionised helium atom
(c) a neutral particle
(d) a doubly-charged helium ion
22. The charge on an electron is equal to:
(a) 1.6 × 10-19 C of -ve charge
(b) 2.6 × 10-19 C of -ve charge
(c) 1.6 × 10-22 C of -ve charge
(d) 1.6 × 10-23 C of -ve charge
23. Isobars do not differ in the number of
(a) protons
(b) electrons
(c) neutrons
(d) nucleons
24. The number of electrons in an atom of Fluorine is 9. Its electronic configuration is
(a) 8, 1
(b) 7, 2
(c) 2, 7
(d) 1, 8
25. Rutherford’s ‘alpha (α) particles scattering experiment’ resulted in the discovery of
(a) electron
(b) proton
(c) nucleus in the atom
(d) atomic mass
26. The valence electrons of an element are reponsible for
(a) Physical properties of an element
(b) Chemical properties of an element
(c) Both the properties
(d) None of these
27. Which isotope is used in the nuclear power plants to generate electricity?
(a) Uranium 235
(b) Iodine 131
(c) Cobalt 60
(d) Uranium 238
28. Cathode rays have
(a) Mass only
(b) Charge only
(c) Both mass and charge
(d) Neither mass nor charge
29. What was the source of alpha particles in Rutherford scattering experiment?
(a) Hydrogen nucleus
(b) Argon nucleus
(c) Helium nucleus
(d) None of these
30. Which of the following is the correct electronic configuration of sodium?
(a) 2, 8, 1
(b) 8, 2, 1
(c) 2, 1, 8
(d) 2, 8, 2
31. If Z = 6, what would be the valency of the element?
(a) 6
(b) 2
(c) 4
(d) 8
32. Which of the following does not match the characteristics of an Isotope?
(a) Isotopes of some elements are radioactive
(b) Isotopes are the atoms of different elements
(c) Isotopes differ in number of neutrons
(d) Isotopes have similar chemical properties
33. Goldstein’s experiments which involved passing high voltage electricity through gases at very low pressure resulted in the discovery of
(a) electron
(b) proton
(c) nucleus
(d) neutron
34. Who used the term ‘ATOM’ for the first time?
(a) Rutherford
(b) John Dalton
(c) Chadwick
(d) Bohr
35. An neutral element A has 3 electrons, the atomic number of an element is
(a) 1
(b) 2
(c) 5
(d) 3
36. Which of the following statement is always correct?
(a) An atom has equal number of electrons and protons
(b) An atom has equal number of electrons and neutrons
(c) An atom has equal number of protons and neutrons
(d) An atom has equal number of electrons, protons and neutrons
37. Neutron Possesses
(a) Positive charge
(b) No charge
(c) Negative charge
(d) None of the above
38. An alpha particle is also known as:
(a) subatomic particle
(b) an unionised helium atom
(c) a neutral particle
(d) a doubly-charged helium ion
39. When a gas at reduced pressure is subjected to an electric discharge, the rays orignating from the negative electrode are–
(a) Cathode rays
(b) Anode rays
(c) x-rays
(d) Radiation ray
40. Which scientist gave the concept of fixed energy levels around the nucleus?
(a) Ernest Rutherford
(b) Neils Bohar
(c) J.J.Thomsan
(d) None of these
41. What prevents an atom from being collapsed?
(a) The nuclear forces
(b) Movement of electrons in discrete energy levels
(c) The electron-electron repulsions
(d) All of these
42. The isotope deuterium of hydrogen has
(a) No neutrons and one proton
(b) One neutrons and two protons
(c) One electron and two neutron
(d) One proton and one neutron
43. The electrons present in the outermost shell are called
(a) Valency electrons
(b) Octate electrons
(c) Duplet electrons
(d) Valence electrons
44. An alpha particle contains
(a) 4 positive charge and 2 mass unit
(b) 2 positive charge and 4 mass unit
(c) 2 positive charge and 2 mass unit
(d) 4 positive charge and 4 mass unit
45. In an alpha scattering experiment, few alpha particles rebounded because
(a) Most of the space in the atom is occupied
(b) charge of the atoms very little Positive space
(c) The mass of the atom is concentrated in the centre
(d) All the positive charge and mass of the atom is concentrated in small volume
46. A tripositive ion has 23 electrons and 30 neutrons. What is the atomic mass of the element?
(a) 56
(b) 53
(c) 50
(d) 55
47. Identify the decreasing order of specific charges of the particles: Electron(e), proton(p), neutron(n) and α particle
(a) e, p, n, α
(b) p, e, n, α
(c) e, p, α, n
(d) n, α, p, e
48. The correct electronic configuration of potassium is
(a) 2, 8, 4
(b) 2, 8, 8, 6
(c) 2, 8, 8, 18
(d) 2, 8, 8, 1
49. In the valence shell, which of the following pairs contains duplet and octet configuration respectively?
(a) Ne, Ar
(b) Ca+2 , O-2
(c) Li+1 , N-3
(d) Mg+2 , Be+2
50. Which of the following set of elements ratio of atomic numbers is 1:2:3:4?
(a) H, He, Li, B
(b) He, Be, C, Ne
(c) Be, O, Mg, Ca
(d) B, Ne, P, Ca
Answer:
| 1-a | 2-b | 3-c | 4-b | 5-c |
| 6-b | 7-c | 8-c | 9-c | 10-a |
| 11-b | 12-c | 13-d | 14-c | 15-b |
| 16-c | 17-c | 18-a | 19-b | 20-b |
| 21-d | 22-a | 23-d | 24-c | 25-c |
| 26-b | 27-a | 28-c | 29-c | 30-a |
| 31-c | 32-b | 33-b | 34-b | 35-d |
| 36-a | 37-b | 38-d | 39-a | 40-b |
| 41-b | 42-d | 43-d | 44-b | 45-b |
| 46-a | 47-c | 48-d | 49-c | 50-d |