Chemistry Class 9 Chapter 2 mcqs Federal Board
Structure of Atoms Important MCQs
- Atoms are so ______ that they can only be visualized by a scanning tunneling microscope.
A.large
B.charged
C.small
D.electronic
Answer: C
Note!!
A scanning tunneling microscope (STM) is a type of microscope used to capture atomic-level images of surfaces.
2. In 1911 ____ performed an experiment in order to know the arrangement of electrons and protons in an atom.

A. Schrodinger
B. Rutherford
C. Bohr
D. Newton
Answer: B
3. Rutherford bombarded a very thin gold foil with ____ particles.

A. Alpha
B. Beta
C. Gamma
D. Tera
Answer: A
4. Rutherford used alpha particles from the disintegration of _____
A. Boron
B. Silicon
C. Tin
D. Polonium
ANSWER : D
5. In Rutherford’s experiment, only one in one million (Alpha particle) was deflected through an angle greater than ___ from their straight path.

A. 97°
B. 90°
C. 180°
D. 100°
Answer: B
6. On the basis of his (Rutherford) experiment he proposed a _____ model for an atom.
A. Geological
B. Mathematical
C. Planetary
D. None of these
Answer: C
7. According to classical physics electron being charged particle will emit energy ____ while revolving around the nucleus.
A. Continuously
B. Discontinuously
C. Slowly
D. Both b & c
Answer: A
8. If a revolving electron emits energy continuously it should form a _______ spectrum.
A. Line
B. Continuous
C. Atomic
D. None of the above
Answer: B

Note !!
- When white light is passed through a prism it is scattered into 7 colors.
- Continuous spectrum:
- In a continuous spectrum, different colors are diffused into one another and not separated by dark spaces.
- Line Spectrum:
- In the line spectrum, different colors are not diffused into one another and are separated by dark spaces.
9. According to Bohr each orbit has a ____ energy.
A. Fixed
B. Variable
C. Large
D. Minute
ANSWER: A
10. According to Bohr energy of an electron is directly proportional to its ___ from the nucleus.
A. size
B. distance
C. electronegativity
D. none of the above
Answer: B
11. Value of Plank’s constant is ____
A. 6.626×10-34 J.s
B. 5.52×1034J.s
C. 9.011×10-31J.s
D. 1.6011×1016 J.s
Answer: A
12. An electron jumps from the K shell to the L shell in this the electron ____ energy.

A. emits
B. donates
C. absorbs
D. none of these
Answer: C
13. Electron present in a particular orbit does not ____ energy.
A. absorbs
B. radiates
C. emits
D. all of these
Answer: D
14. According to Bohr mvr =
A. nh/2V
B. nh/4π
C. nh/4V
D. nh/2π
ANSWER: D
15. Which one of the following is correct according to Bohr’s model?
A. ΔE =E3 – v
B. ΔE=E2 –E1
C. ΔE=F.s
D. All of these
Answer: B
16. Which of the following is true for isotopes?
A. they have the same number of neutron
B. they have the same atomic mass
C. they have the same atomic number
D. all of these
Answer: C
17. Isotopes have different atomic mass due to ____
A. different number of electrons
B. different number of protons
C. different number of neutron
D. different atomic number
Answer: C
18. Isotopes are ____ alike.
A. chemically
B. physically
C. neutral
D. none of the above
ANSWER: A
19. Physical properties of an element depend upon its _____.
A. Atomic number
B. Protons
C. Electrons
D. Atomic mass
Answer 😀
20. Atomic mass can also be called ___.
A. electron affinity
B. mass number
C. nucleon number
D. both b & c
Answer: D
21. The first man to use the word “isotope” was ___.
A. Einstein
B. Sodday
C. Newton
D. G.N Lewis
ANSWER: B
22. Hydrogen has __ isotopes.
A. 4
B. 6
C. 3
D. 5
Answer: C
23. Tritium has how many neutrons?
A. 0
B. 1
C. 2
D. 3
Answer: C
24. Melting point of heavy water is __ °C.
A. 0
B. 3.81
C. 4.3
D. 5.4
Answer: B
Note!!
Heavy water (D2O) also referred to as deuterium oxide.
25. The number of isotopes of carbon are ___
A. 2
B. 4
C. 3
D. 6
Answer: C
26. Natural abundance of C-12 = __
A. 98.8%
B. 99%
C. 97%
D. 99.7
Answer: A
27. Chlorine has how many isotopes?
A. 3
B. 4
C. 5
D. 2
Answer: D
28.Chlorine-37 occurs in nature at about ___%.
A. 75.78%
B. 24.23%
C. 35%
D. 65%
Answer: B
29. Chlorine is fairly __ in water.
A. insoluble
B. soluble
C. reactive
D. none of these
Answer: B
30. Chlorine is a greyish ___ gas with a sharp pungent irritating smell.
A. pink
B. blue
C. red
D. yellow
Answer: D
31. If Uranium(234U) has 92 protons then it has __ number of neutrons.
A. 142
B. 134
C. 122
D. none of the above
Answer: A
32. Radioactive iodine -131 is used as a tracer in diagnosing ___ problem.
A. ulcer
B. lungs
C. heart
D. thyroid
Answer: D
33. Cobalt-60 is commonly used to irradiate ___ Cells in the hope of killing or shrinking the tumors.
A. nerve
B. red blood cells
C. cancer
D. white blood cells
Answer : C
34. As the value of n___ the distance of an electron from the nucleus and the energy of the shell increases.
A. increases
B. decreases
C. stays the same
D. All of these
Answer: A
35. s sub-shell can accommodate maximum _ electrons.
A. 3
B. 4
C. 2
D. 6
Answer: C
36. f sub-shell can accommodate maximum electrons.
A. 14
B. 12
C. 10
D. 8
Answer: A
37. 1s < 2s < 2p < 3s < 3p<4s < __ .
A. 3d
B. 4s
C. 4p
D. 5s
Answer: A
38. 11Na=1s2,2s2,2p6 __ .
A. 3p1
B. 3d10
C. 4s1
D. 3s1
Answer: D
39. Using Bohr’s formula i.e 2n2, determine the number of electrons that can be added into M – shell .
A. 12
B. 18
C. 8
D. 28
Answer: B
40. If an element has 20 electrons how many sub-shells will it have?
A. 2
B. 3
C. 4
D. 6
Answer: D
41.___ subshell is spherical shaped.
A. s
B. p
C. d
D. f
Answer: A
42. ___ subshell has a very complicated shape.
A. s
B. p
C. d
D. f
Answer: D
43. Heavy water is made by using ___.
A. protium
B. deuterium
C. tritium
D. none of these
Answer: B
44. Boiling point of water is ___ .
A. 101°C
B. 100°C
C. 102°C
D. 103°C
Answer: B
45. L shell can accommodate a maximum of ___ electrons.
A. 3
B. 2
C. 8
D. 6
Answer: C
46. Which one of the following shell has the lowest energy?
A. L
B. N
C. M
D. K
Answer: D
47. How many neutrons are there in chlorine – 37 if it has 17 electrons?
A. 21
B. 20
C. 19
D. 12
Answer: B
48. d Sub shell has ___ shape.
A. spherical
B. dumbell
C. double dumbell
D. none of them
Answer: C
49. Keeping in mind the Auf Bau principle the electron will first enter into which subshell?
A. 3s
B. 1s
C. 2s
D. 4s
Answer: B
50. How many neutrons are there in 27M if its atomic number is 13?
A. 12
B. 13
C. 14
D. 16
Answer: C
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