Hello students. Are you looking for multiple choice questions from the chapter "Structure of Atom"? You are on the right place.
In this article, we will be providing you with MCQ questions from the chapter "Structure of Atom". These objective questions will help you in your preparation for CBSE as well as competitive exams. Good Luck!
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Questions
1. Choose the incorrect relation on the basis of Bohr’s theory
a) Velocity of electron ∝1/n
b) Frequency of revolution ∝1/n2
c) Radius of orbit ∝n2 Z
d) Force on electron ∝1/n4
2. X-rays were discovered by :
a) Becquerel
b) Roentgen
c) Mme. Curie
d) Van Laue
3. Two electrons in the same orbital may be identified with:
a) n
b) l
c) m
d) s
4. An electron has principal quantum number 3. The number of its (i) subshells and (ii) orbitals would be respectively:
a) 3 and 5
b) 3 and 7
c) 3 and 9
d) 2 and 5
5. Maximum number of electrons in a subshell of an atom is determined by the following:
a) 2n2
b) 4l+2
c) 2l+1
d) 4l-2
6. Particle having mass 200 times that of an electron is:
a) Proton
b) Positron
c) Meson
d) Neutron
7. Which of the following has the maximum number of unpaired electrons?
a) Mg2+
b) Ti3+
c) Fe2+
d) V3+
8. An electron from one Bohr stationary orbit can go to next higher orbit
a) By emission of electromagnetic radiation
b) By absorption of any electromagnetic radiation
c) By absorption of electromagnetic radiation of particular frequency
d) Without emission or absorption of electromagnetic radiation
9. How many neutrons are present in tritium nucleus?
a) 2
b) 3
c) 1
d) 0
10. The number of wave made by an electron moving in an orbit having maximum magnetic quantum number +3 is :
a) 4
b) 3
c) 5
d) 6
11. The wavelength of a spectral line emitted by hydrogen atom in the Lyman series is 16/15R cm. What is the value of n2?(R=Rydberg constant)
a) 2
b) 3
c) 4
d) 1
12. The statements, which is/are correct:
a) Number of total nodes in an orbital =n-1
b) Number of radial nodes in an orbital =n-l-1
c) Number of angular nodes in an orbital =l
d) All of the above
13. If the wavelength of an electromagnetic radiation is 2000Å, what is its energy in ergs?
a) 9.94×10-12
b) 9.94×10-19
c) 4.97×10-12
d) 4.97×10-19
14. Number of unpaired electrons in the electronic configuration 1s2, 2s2 2p4:
a) 2
b) 3
c) 4
d) 6
15. A strong argument for the particle nature of cathode rays is that they:
a) Produce fluorescence
b) Travel through vacuum
c) Get deflected by electric and magnetic fields
d) Cast shadow
16. The electronic configuration 1s2, 2s2 2p6, 3s1 3p1 correctly describes:
a) Ground state of Na
b) Ground state of Si+
c) Excited state of Mg
d) Excited state of Al3+
17. What accelerating potential is needed to produce an electron beam with an effective wavelength of 0.090Å?
a) 1.86×104 eV
b) 1.86×102 eV
c) 2.86×104 eV
d) 2.86×102 eV
18. Which of the following pairs have identical values of e/m?
a) A proton and a neutron
b) A proton and deuterium
c) Deuterium and an α-particles
d) An electron and γ-rays
19. Positive charge in an atom is:
a) Scattered all over the atom
b) Concentrated in the nucleus
c) Revolving around the nucleus
d) None is true
20. [Cr(H2O)6]Cl3 (at. No. of Cr=24) has a magnetic moment of 3.83 B.M. The correct distribution of 3d electrons in the chromium of the complex:
a) 3dxy1, 3dyz1, 3dxz1
b) 3sxy1, 3dyz1, 3dz21
c) 3dx2-y21, 3dz21, 3dxz1
d) 3dxy1, 3dx2-y21, 3dyz1
Answers
1. c 2. b 3. d 4. c 5. b 6. c 7. c 8. c 9. a 10. a 11. c 12. d 13. a 14. a 15. c 16. c 17. a 18. c 19. b 20. a
Solutions
2 (b)
Roentgen discovered X-rays.
3 (d)
Spins of an electron are ±1/2 in an orbital
4 (c)
No. of subshell= n; no. of orbitals= n2.
5 (b)
No. of electrons in an orbital = 2
No. of orbitals in a subshell = 2l+1
∴ No. of electrons in an orbital = 2(2l+1)
6 (c)
Mesons are electrically neutral (π0) or charged (π-, π+) particles having their mass 236 times of electron.
7 (c)
Mg^(2+)=[Ne] [Zero unpaired electrons]
Ti^(3+)=[Ar]3d1[One unpaired electrons]
Fe^(2+)=[Ar]3d^5[Five unpaired electrons]
V^(3+)=[Ar]3d2[Two unpaired electrons]
8 (c)
According to Bohr’s atomic model, if energy is supplied to an electron it may jump from a lower energy level to higher energy level. Energy is absorbed in the form of quanta (or photon).
∆E=hv
Where, v is the frequency.
According to above postulate an electron from one Bohr stationary orbit can go to next higher orbit by the absorption of electromagnetic radiation of particular frequency.
9 (a)
Tritium is the isotope of hydrogen. Its composition is as follows :
1 electron, 1 proton and 2 neutrons
10 (a)
If m= +3 (maximum), then l=3 (maximum). Thus, maximum value of n= 4. Also no. of waves in an orbit = no. of orbit
11 (c)
For Lyman series,
12 (d)
The desired formulae to calculate nodes.
13 (a)
14 (a)
In p-orbitals electrons are present as
15 (c)
Rest all are evidence for wave nature.
16 (c)
Ground state of 12Mg is 1s2, 2s22p6, 3s2.
17 (a)
18 (c)
So, deuterium and an α-particles have identical value of e/m
19 (b)
All the protons carrying +ve charge are present in nucleus.
20 (a)
Cr3+:1s2, 2s22p6, 3s23p63d3.
The 3dxy1, 3dxz1, 3dyz1 has lower energy.
These were the 20 questions from this chapter. You can comment below to find more questions.