MCQ Questions for Class 9 Science Chapter 4 Structure of the Atom

Q.1.   The nucleons are           
(a) Protons and electrons          
(b) Neutrons and electrons        
(c) Protons and neutrons        
(d) None of these

Answer Answer:
(c)

Q.2. Which isotope is used in the nuclear power plants to generate electricity?
(a) Uranium 235
(b) Iodine 131
(c) Cobalt 60
(d) Uranium 238

Answer Answer:
(a)

Q.3. Who discovered the electron?
(a) Rutherford
(b) Chadwick
(c) Thomson
(d) Goldstein

Answer Answer:
(c)

Q.4. What was the source of alpha particles in Rutherford scattering experiment?
(a) Hydrogen nucleus
(b) Argon nucleus
(c) Helium nucleus
(d) None of these

Answer Answer:
(c)

Q.5. Why was the Thomson’s Model of an atom failed?
i. It could not explain the screening of negative charges from that of positive
ii. It did not tell about the presence of electrons
iii. It did not give an idea about the discrete energy levels
iv. It explained the atom as a whole to be electrically neutral.
Choose the correct option from the following:
(a) Only (iii)
(b) Both (i) & (iii)
(c) Only (i)
(d) Both (ii) & (iv)

Answer Answer:
(b)

Q.6. What property of an element determines its chemical behaviour?
(a) Size of an element
(b) Valency of an element
(c) Molar mass of the element
(d) None of these

Answer Answer:
(b)

Q.7. 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

Answer Answer:
(b)

Q.8. Which of the two will be chemically more reactive, Sulphur(S) with atomic number 16 or Chlorine (Cl) with atomic number 17?
(a) Chlorine
(b) Sulphur
(c) Both are equally reactive
(d) Can’t say

Answer Answer:
(a)

Q.9. Which of the following statements is incorrect about the structure of an atom?
i. The whole mass of an atom is concentrated in the nucleus
ii. The atom is an indivisible particle
iii. The atom as a whole is neutral
iv. All the atoms are stable in their basic state
Choose the right option among the following:
(a) (i) and (iii)
(b) only  (ii)
(c) (ii) and (iv)
(d) none of these

Answer Answer:
(c)

Q.10. Which of the following elements does not exhibit the electrovalencey?
(a) Sodium
(b) Calcium
(c) Carbon
(d) Chlorine

Answer Answer:
(c)

Q.11. 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

Answer Answer:
(b)

 Q.12. 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

Answer Answer:
(b)

Q.13. Which of the following is an incorrect statement in reference with observation in Rutherford’s α-particle scattering experiment?
(a) Some of the α-particles rebound after hitting the gold foil 
(b) Some of the particles deflected from their path
(c) Some of the particles not pass through the gold foil 
(d) Most of the particles pass straight through the gold foil

Answer Answer:
(a)

Q.14. Which of the following pairs are isobars?
(a) 17Cl35 & 17Cl37
(b)  18Ar40 & 20Ca40
(c)  6C12 & 6C14
(d) None of these

Answer Answer:
(b)

Q.15. Which radioactive element is used in the treatment of cancer?
(a) Iodine-131
(b) Uranium-234
(c) Plutonium-239
(d) Cobalt-60

Answer Answer:
(d)

Q.16. Why do most of the elements try to participate in the chemical combinations?
i. To gain more electrons
ii. To achieve Inert Gas configuration
iii. To complete their octet
iv. To complete their inner shells
Choose the correct option among the following
(a) Both (i) & (iii)
(b) Both (ii) & (iii)
(c) Only (ii)
(d) Both (i) & (iv)

Answer Answer:
(b)

Q.17.   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

Answer Answer:
(d)

Q.18.   The electrons present in the outermost shell are called           
(a) Valency electrons          
(b) Octate electrons        
(c) Duplet electrons        
(d) Valence electrons

Answer Answer:
(d)

Q.19.   The atomic number of sodium is 11 and its mass number is 23. It has           
(a) 11 neutrons and 12 protons          
(b) 12 protons and 11 electrons        
(c) 11 electrons and 12 neutrons        
(d) 12 electrons and 11 neutrons

Answer Answer:
(c)

Q.20.   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

Answer Answer:
(b)

Q.21.  The electronic configuration of chlorine is           
(a) 2,7          
(b) 2,8,8,7        
(c) 2,8,7        
(d) 2,7,8

Answer Answer:
(c)

Q.22.   In an alpha scattering experiment, few alpha particles rebounded because           
(a) Most of the space in the atom is occupied          
(b) Positive charge of the atoms very little 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

Answer Answer:
(b)

Q.23.   The isotope used to remove the brain tumours and treatment of cancer is           
(a) U-235          
(b) Na-24        
(c) Iodine        
(d) C0-60

Answer Answer:
(d)

You may also check the MCQs on other chapters from the links provided below:

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Also Check:

CBSE Class 9 Science Study Notes

CBSE Class 9 Science Chapter Wise MCQ Questions

NCERT Solutions for Class 9 Science

NCERT Solutions for Class 9 Maths

Lakhmir Singh Class 9 Science Solutions

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