Looking for MCQ questions for Class 9 Science Chapter 4? Explore our comprehensive collection of Structure of the Atom MCQ Science Class 9 with answers. These multiple-choice questions cover various topics such as atomic structure, subatomic particles, atomic models, and more. Whether you’re a student preparing for exams or a teacher seeking additional resources, our MCQs provide a valuable tool for learning and assessment. Enhance your understanding of the atom’s structure and boost your performance with these carefully crafted questions and accurate answers.
MCQ Questions for Class 9 Science Chapter 4 Structure of the Atom with Answers
Q1. E. Goldstein in 1886 discovered the presence of new radiations in a gas discharge and called them :-
a) a-particles ray
b) electron rays
c) cathode rays
d) canal rays
Ans :- canal rays
Q2. The Proton’s is approximately ___________ as that of the electron.
a) 1000 times
b) 1500 times
c) 2000 times
d) None of these
Ans :- 2000 times
Q3. What are canal rays ?
a) Positively charged radiations
b) Negatively charged radiations
c) Neutral radiations
d) None of the above
Ans :- Positively charged radiations
Q4. Who was the first scientist to propose the model for the structure of the atom ?
a) J.J. Thomson
b) E. Rutherford
c) Neils Bohr
d) All of them
Ans :- J.J. Thomson
Q5. According to Thomson’s model an atom is similar to that of :-
a) Christmas pudding
b) Watermelon
c) Both (a) and (b)
d) None (a) and (b)
Ans :- Both (a) and (b)
Q6. Which of the following statements is true about Thomson’s model of an atom ?
i) The mass of the atom is assumed to be uniformly distributed over the atom.
ii) The electrons attract each other to stabilize the atom.
iii) The electrons are uniformly distributed in the positive charge sphere
iv) The positive charge is assumed to be uniformly distributed over the atom.
a) (i), (ii) and (iii) are true
b) (ii), (iii) and (iv) are true
c) (i), (iii) and (iv) are true
d) (i), (ii) and (iv) are true
Ans :- (i), (iii) and (iv) are true
Q7. Why is the atom electrically neutral by Thomson’ model ?
a) because positive charges are high in magnitude.
b) because negative and positive charges are equal in magnitude.
c) because neutron are neutral
d) None of these
Ans :- because negative and positive charges are equal in magnitude.
Q8. ________ are studded in the positively charged sphere, like the seeds in the watermelon.
a) Electrons
b) Protons
c) Neutrons
d) All of these
Ans :- Electrons
Q9. What are Alpha-particles
a) singly-charged helium ions and having mass of 2u
b) neutral helium ions and having mass of 3u
c) Doubly-charged helium ions and having mass of 4u
d) None of these
Ans :- Doubly-charged helium ions and having mass of 4u
Q10. Rutherford’s alpha-particle scattering experiment was responsible for the discovery of
a) Protons
b) Electrons
c) Nucleus
d) None of these
Ans :- Nucleus
Q11. Which facts of the atom does the Rutherford’s alpha-particle experiment shows us :-
i) The mass and the positive charge of the atom is concentrated in the nucleus
ii) Neutron exists in the nucleus
iii) Most of the space ie empty in the atom
iv) Electron have negative charge
a) (i) and (ii) is showed by the experiment
b) (i) and (iv) is showed by the experiment
c) (ii) and (iii) is showed by the experiment
d) (i) and (iii) is showed by the experiment
Ans :- (i) and (iii) is showed by the experiment
Q12. Rutherford calculated the radius of the nucleus is about _______ less than the radius of the atom.
a) 10³ times
b) 10⁵ times
c) 10⁷ times
d) 10⁹ times
Ans :- 10⁵ times
Q13. All mass of an atom resides in the ________.
a) nucleus
b) Protons
c) Electrons
d) All of these
Ans :- nucleus
Q14. Which of the following conclusions of Rutherford’s experiment is true ?
a) most of the space inside the atom is empty
b) the positive charge of the atom occupies very little space
c) all the positive charge and the mass of the gold atom work concentrated in a very small volume within the atom
d) All of these
Ans :- All of these
Q15. Which of the following statements is true about the nuclear model of an atom ?
a) the electrons revolve around the nucleus in circular paths
b) the size of the nucleus is very small as compared to the size of the atom
c) In atom the positively charged nucleus has all masses of that atom
d) All of these
Ans :- All of these
Q16. Most of the fast moving alpha-particles _____________ through the gold foil.
a) were deflected by small angles
b) were deflected by big angles
c) passes straight
d) were rebound
Ans :- passes straight
Q17. Surprisingly, In the experiment of Rutherford’s model, One out of every _____________ appeared to rebound.
a) 12000 particles
b) 2000 particles
c) 1200 particles
d) None of these
Ans :- 12000 particles
Q18. Which of the following statements is correct/true about Rutherford’s model of an atom?
i) It was in agreement with E. Goldstein
ii) It can similar to the solar system
iii) considered that the nucleus is Positively charged
iv) Established that the Alpha-particles are four times heavier as hydrogen atom
a) (i) statement is correct
b) (ii) and (iii) statement are correct
c) (i) and (iii) statement are correct
d) (ii) and (iv) statement are correct
Ans :- (ii) and (iii) statement are correct
Q19. Any particle in a circular orbit would undergo ________
a) change in state
b) free fall
c) acceleration
d) none of the above
Ans :- acceleration
Q20. While revolving in discrete orbits the electrons do not ________.
a) radiate power
b) radiate particles
c) radiate energy
d) All of these
Ans :- radiate energy
Q21. The maximum number of electrons that can be accommodated in the outermost orbit is :-
a) 8 electrons
b) 18 elections
c) 32 electrons
d) It can be infinite electrons
Ans :- 8 electrons
Q22. What are Neutrons ?
a) subatomic particle which have charge and mass equal to the atomic number
b) subatomic particle which have no charge and mass nearly equal to the mass of protons
c) subatomic particle which have no charge and mass nearly equal to the mass of electrons
d) none of the above
Ans :- subatomic particle which have no charge and mass nearly equal to the mass of protons
Q23. What are valence electrons ?
a) the electrons present in the innermost shell of an atom
b) the electrons present in the outermost shell of an atom
c) the electrons present in the middle shell of an atom
d) none of these
Ans :- the electrons present in the outermost shell of an atom
Q24. What is the Valency of phosphorus (P) ?
a) 3 valency
b) 5 valency
c) none (a) and (b)
d) both (a) and (b)
Ans :- both (a) and (b)
Q25. An atom of each element has a definite combining capacity is called its :-
a) octet power
b) valence electrons
c) valency
d) none of these
Ans :- valency
Q26. What is an atomic number ?
a) total number of neutrons present in nucleus
b) total number of protons present in nucleus
c) total number of electrons present in nucleus
d) none of the above
Ans :- total number of protons present in nucleus
Q27. The mass number of an atom is defined as :-
a) sum of the total number of electrons and neutrons present in the nucleus of an atom
b) sum of the total number of protons and electrons present in the nucleus of an atom
c) sum of the total number of protons and neutrons present in the nucleus of an atom
d) none of these
Ans :- sum of the total number of protons and neutrons present in the nucleus of an atom
Q28. Which statement is true about the ‘Isotopes’ :-
i) the atoms of the same element, having same atomic number but different mass number
ii) the atoms of the different element, having different atomic number but same mass number
iii) they have different chemical properties but same physical properties
iv) they have same chemical properties but different physical properties
a) (i) and (ii) are true
b) (ii) and (iii) are true
c) (ii) and (iv) are true
d) (i) and (iv) are true
Ans :- (i) and (iv) are true statement
Q29. What are the uses of isotopes?
a) An isotope of uranium is used as a fuel in nuclear reactors.
b) An isotope of cobalt is used in the treatment of cancer.
c) An isotope of iodine is used in the treatment of goitre.
d) All of the above
Ans :- All of the above
Q30. Isobars are defined as :-
a) Atoms of different elements with different atomic numbers, which have the same mass number
b) Atoms of different elements with same atomic numbers, which have the same mass number
c) Atoms of same element with same atomic number but different mass number
d) None of the above
Ans :- Atoms of different elements with different atomic numbers, which have the same mass number