Class 9 Science Chapter 8 | MCQ

NCERT Class 9 Science MCQ | Chapter 8: Journey Inside The Atom

1. According to the chapter, matter is ultimately composed of:
(A) Cells
(B) Molecules only
(C) Atoms
(D) Tissues
Answer: (C)

2. Who suggested the concept of “parmanus” in ancient India?
(A) Acharya Kanada
(B) John Dalton
(C) J. J. Thomson
(D) Ernest Rutherford
Answer: (A)

3. The Greek word “atomos” means:
(A) Particle
(B) Indivisible
(C) Energy
(D) Charge
Answer: (B)

4. John Dalton proposed his atomic theory in:
(A) 1897
(B) 1911
(C) 1808
(D) 1932
Answer: (C)

5. According to Dalton’s original atomic theory, atoms were considered:
(A) Divisible particles
(B) Indivisible particles
(C) Positively charged particles
(D) Electrically negative particles
Answer: (B)

6. The discovery of which phenomenon showed that atoms were not indivisible?
(A) Gravitation
(B) Radioactivity
(C) Reflection
(D) Evaporation
Answer: (B)

7. J. J. Thomson discovered the:
(A) Proton
(B) Neutron
(C) Electron
(D) Nucleus
Answer: (C)

8. Cathode rays were found to consist of:
(A) Positively charged particles
(B) Negatively charged particles
(C) Neutral particles
(D) Neutrons
Answer: (B)

9. The charge of an electron is conventionally taken as:
(A) +1
(B) 0
(C) +2
(D) -1
Answer: (D)

10. Thomson proposed that an atom consists of:
(A) A positively charged sphere with electrons embedded in it
(B) A nucleus surrounded by neutrons
(C) Only electrons
(D) A positively charged nucleus with no electrons
Answer: (A)

11. Thomson’s atomic model is commonly called the:
(A) Planetary model
(B) Nuclear model
(C) Plum pudding model
(D) Energy-level model
Answer: (C)

12. In Thomson’s model, the positive charge was:
(A) Concentrated in the nucleus
(B) Distributed throughout the atom
(C) Present only in electrons
(D) Absent from the atom
Answer: (B)

13. The gold foil experiment was carried out by Geiger and Marsden under:
(A) John Dalton
(B) J. J. Thomson
(C) Niels Bohr
(D) Ernest Rutherford
Answer: (D)

14. The particles used in Rutherford’s gold foil experiment were:
(A) Beta particles
(B) Electrons
(C) Alpha particles
(D) Neutrons
Answer: (C)

15. Most alpha particles in Rutherford’s experiment:
(A) Bounced back
(B) Passed through the foil undeflected
(C) Were absorbed by the foil
(D) Stopped immediately
Answer: (B)

16. The large deflection of a few alpha particles suggested that:
(A) The atom was completely solid
(B) Electrons were positively charged
(C) Most of the atom was empty
(D) Positive charge and most mass were concentrated in a tiny region
Answer: (D)

17. Rutherford called the small, dense, positively charged region at the centre of an atom the:
(A) Shell
(B) Nucleus
(C) Orbit
(D) Electron cloud
Answer: (B)

18. According to Rutherford’s model, most of an atom is:
(A) Empty space
(B) Filled with electrons
(C) Filled with neutrons
(D) Filled with positive charge
Answer: (A)

19. Rutherford’s model could not explain:
(A) The existence of the nucleus
(B) The scattering of alpha particles
(C) The stability of atoms
(D) The positive charge of the nucleus
Answer: (C)

20. According to Rutherford’s model, electrons:
(A) Were embedded in a positive sphere
(B) Revolved around the nucleus
(C) Were present inside the nucleus
(D) Had no motion
Answer: (B)

21. The proton was associated with the positive charge of the:
(A) Electron cloud
(B) Shell
(C) Nucleus
(D) Orbit
Answer: (C)

22. In a neutral atom, the number of protons is:
(A) Greater than the number of electrons
(B) Less than the number of electrons
(C) Equal to the number of electrons
(D) Equal to the number of neutrons only
Answer: (C)

23. Niels Bohr proposed his atomic model in:
(A) 1808
(B) 1897
(C) 1911
(D) 1913
Answer: (D)

24. According to Bohr’s model, electrons move around the nucleus in:
(A) Random paths
(B) Fixed energy levels
(C) Straight lines
(D) The nucleus itself
Answer: (B)

25. The first shell of an atom is called:
(A) K-shell
(B) L-shell
(C) M-shell
(D) N-shell
Answer: (A)

26. The energy of an electron generally increases as it moves:
(A) Closer to the nucleus
(B) Towards the K-shell
(C) Away from the nucleus
(D) Into the nucleus
Answer: (C)

27. An electron moving in a fixed shell according to Bohr’s model:
(A) Continuously loses energy
(B) Does not lose energy
(C) Loses its charge
(D) Becomes a proton
Answer: (B)

28. An electron can move from one energy level to another by:
(A) Absorbing or releasing a fixed amount of energy
(B) Losing its mass
(C) Changing into a neutron
(D) Changing its atomic number
Answer: (A)

29. The maximum number of electrons that can be accommodated in a shell is given by:
(A) n²
(B) 2n
(C) 2n²
(D) n/2
Answer: (C)

30. The maximum number of electrons that can be accommodated in the K-shell is:
(A) 1
(B) 2
(C) 8
(D) 18
Answer: (B)

31. The maximum number of electrons that can be accommodated in the L-shell is:
(A) 2
(B) 4
(C) 8
(D) 18
Answer: (C)

32. The maximum number of electrons that can be accommodated in the M-shell according to 2n² is:
(A) 8
(B) 18
(C) 16
(D) 32
Answer: (B)

33. The maximum number of electrons generally allowed in the outermost shell is:
(A) 2
(B) 4
(C) 8
(D) 18
Answer: (C)

34. Which subatomic particle has no electrical charge?
(A) Electron
(B) Proton
(C) Neutron
(D) Alpha particle
Answer: (C)

35. The neutron was discovered by:
(A) James Chadwick
(B) J. J. Thomson
(C) Ernest Rutherford
(D) Niels Bohr
Answer: (A)

36. The relative charge of a proton is:
(A) -1
(B) 0
(C) +1
(D) +2
Answer: (C)

37. The relative charge of a neutron is:
(A) +1
(B) -1
(C) +2
(D) 0
Answer: (D)

38. The atomic number of an element is equal to the number of:
(A) Neutrons
(B) Protons
(C) Protons + neutrons
(D) Electrons + neutrons
Answer: (B)

39. The symbol used for atomic number is:
(A) A
(B) N
(C) Z
(D) P
Answer: (C)

40. The mass number of an atom is equal to:
(A) Number of electrons + protons
(B) Number of protons + neutrons
(C) Number of electrons + neutrons
(D) Number of protons – neutrons
Answer: (B)

41. The symbol used for mass number is:
(A) A
(B) Z
(C) E
(D) N
Answer: (A)

42. An atom has 11 protons and 12 neutrons. Its mass number is:
(A) 11
(B) 12
(C) 22
(D) 23
Answer: (D)

43. An atom has atomic number 17 and mass number 35. The number of neutrons is:
(A) 17
(B) 18
(C) 35
(D) 52
Answer: (B)

44. The outermost shell of an atom containing electrons is called the:
(A) Nuclear shell
(B) Valence shell
(C) Proton shell
(D) Inner shell
Answer: (B)

45. The electrons present in the outermost shell are called:
(A) Nuclear electrons
(B) Free electrons
(C) Valence electrons
(D) Core protons
Answer: (C)

46. The combining capacity of an atom is called:
(A) Atomic number
(B) Mass number
(C) Valency
(D) Isotope
Answer: (C)

47. An atom with a complete octet in its outermost shell is generally:
(A) More reactive
(B) Stable and largely unreactive
(C) Positively charged
(D) Unable to contain electrons
Answer: (B)

48. Atoms of the same element having the same atomic number but different mass numbers are called:
(A) Isobars
(B) Ions
(C) Isotopes
(D) Molecules
Answer: (C)

49. Atoms of different elements having the same mass number but different atomic numbers are called:
(A) Isotopes
(B) Isobars
(C) Ions
(D) Nucleons
Answer: (B)

50. Chlorine has isotopes of masses 35 u and 37 u occurring in approximately 75% and 25% abundance respectively. Its weighted average atomic mass is:
(A) 35.0 u
(B) 36.0 u
(C) 35.5 u
(D) 37.0 u
Answer: (C)

NCERT Class 9 Science MCQ | Chapter 8: Journey Inside The Atom

ASSERTION–REASON QUESTIONS

Q1. Assertion (A): Rutherford concluded that most of the mass of an atom is concentrated in a very small region called the nucleus.

Reason (R): Most alpha particles passed through the gold foil without deflection, while a few were deflected through large angles.