NCERT Class 11 Chemistry Chapter 2 Structure Of Atom Very Question And Answers

NCERT Solutions For Class 11 Chemistry Chapter 2 Structure Of Atom Very Short Question And Answers

Question 1. What is the value of the elm of an electron?
Answer: 1.76 × 108Cg-1

Question 2. How many times a proton is heavier than an electron?
Answer: 1837 times (approx.),

Question 3. Mention one similarity between isobar and isotone-
Answer: Atoms of different elements,

Question 4. What is wave number?
Answer: No. of waves in 1 cm,

Question 5. Arrange in order of the increasing wavelength
Answer: γ-ray

Question 6. What is meant by stationary orbit?
Answer: Orbits in which the energy of revolving electrons remains fixed

Question 7. Who proposed the quantum theory of radiation?
Answer: M. Planck

Question 8. What is the value of Planck’s constant in the SI unit?
Answer: 6.626 × 10-34

Question 9. What is the value of the angular momentum of an electron occupying the second orbit in an atom?
Answer: \(\frac{h}{\pi}\)

Question 10. Mention the symbol and the mass number of an element which contains two neutrons in the nucleus.
Answer: \({ }_2^4 \mathrm{He}\)

Question 11. Why is the spectrum of H+ not obtained?
Answer: Because H+ does not contain any electrons,

Question 12. How many proton(s) & electron(s) are in Hion?  
Answer: One proton and two electrons,

Question 13. From which principal energy state, the excited electron comes down to yield spectral lines in the Balmer series?
Answer: L-shell (n = 2),

Question 14. How many neutrons are present in and 20 40 Ca 2+
Answer: 20 neutrons,

Question 15. What is the nature of hydrogen spectra?
Answer: Discontinuous spectrum or line spectrum,

Question 16. Mention one ion that obeys Bohr’s theory.
Answer: He+,

Question 17. Write the relationship between wavelength and momentum of a moving microscopic particle. Who proposed this relationship?
Answer: \(\lambda=\frac{h}{m v}\)

Question 18. Indicate the limitation of Broglie’s equation.
Answer: Not applicable to macroscopic particles,

Question 19. Is the uncertainty principle applicable to stationary electrons?
Answer: Not applicable

Question 20. Energy associated with which of the following waves is not quantized?

  • Electromagnetic wave
  • Matter-wave

Answer: Matter waves,

Question 21. What is an orbital according to the quantum mechanical model?
Answer: The region around the nucleus has the maximum probability of finding an electron,

Question 22. How do you specify an electron in an atom?
Answer: By using four quantum numbers (n, l, m and s),

Question 23. What is the maximum number of orbitals in the ‘j’th orbit?
Answer: n²,

Question 24. Which is the lowest energy level containing ‘g1 sub-shell?
Answer:  n = 5 (fifth shell),

Question 25. Identify the orbital with n = 4 and 1 = 0.
Answer: 4s,

Question 26. Which ‘d’-orbital does not contain four lobes?
Answer: dz2

Question 27. Which quantum electron?
Answer: Azimuthal quantum number (l),

Question 28. Write the electronic configuration of Mn
Answer: ls22s22p53s2 3p63d5,

Question 29. What is the total number of nodes in 3d -orbital?
Answer:

Total no. of nodes =(n-1)

= 3- 1

= 2

Question 30. Which subshell has the lowest screening power?
Answer: f

Question 31. Which quantum number is used to distinguish between the electrons present in a single orbital?
Answer: Spin quantum number, S,

Question 32. What are the quantum numbers used to indicate the size and shape of orbitals?
Answer: Principal & azimuthal quantum numbers,

Question 33. State the condition under which electronic energy is considered to be negative.
Answer: When the electron is at an infinite distance from the nucleus ( n = ∞ )

Question 34. What are the fundamental constituents____of atom?
Answer: Electrons, protons, and neutrons are the fundamental constituents of an atom.

Question 35. Name the clement containing no neutron.
Answer: Ordinary hydrogen atom or protium:

Question 36. Name the anode ray particle with the highest value.
Answer: The e/m value of proton (H+ ion) has the highest value.

Question 37. What is the consequence when cathode rays strike a hard metal surface like tungsten?
Answer: X-rays are produced.

Question 38. Why is an electron called a universal particle?
Answer: Its mass and charge are independent of its source

Question 39. What is the value of a fundamental unit of electricity?
Answer: The charge carried by one electron is said to be the fundamental unit of electricity. Its magnitude is 4.8 × 10-19 esu or 1.602 × 10-19 C.

Question 40. Besides electron, proton, and neutron, name two other subatomic particles.
Answer: Positron (+1e 0 ) and Neutrino (0v0 ).

Question 41. Out of X-rays, γ-rays, and microwaves which one has die highest and which one has die lowest frequency?
Answer:

Highest frequency: γ-rays

Lowest frequency: Microwave

Question 42. Arrange the given subshells in the increasing order of their energies: 3d, 4p, 4s, 5p, 4d, 6s, 4f.
Answer:

The sequence of energy of the given subshells is 4s < 3d < 4p < 4d < 5p < 6s < 4.

Question 43. What is the main difference between a wave emitted by an electric bulb and that associated with a tiny particle moving at a very high speed?
Answer: The bulb emits electromagnetic waves, while that associated with the moving particle is matter.

Question 44. At what distance from the nucleus is the radial probability maximum for the Is -orbital of the hydrogen atom? What is this distance called?
Answer: At a distance of 0.529Å, the radial probability is maximum. This distance is called the Bohr radius.

Question 45. In which shell(s), there is no existence of d -subshell?
Answer: There is no existence of ‘d’ subshell in K and L -shells

Question 46. Out of the four quantum numbers which one does not result from the solution of the Schrodinger wave equation?
Answer: Spin quantum number.

Quantum 47. The 4f-subshell of an atom contains 12 electrons. What is the maximum number of electrons having spins in the same direction?
Answer: Seven electrons have spin in the same direction.

Question 48. What is the lowest value of n that allows g-orbitals to exist?
Answer: For the existence of g-subshell, 1 should be 4. For a given orbital, the maximum value of 1 = (n-1). Thus, for 1 = 4, the minimum value of n should be 5.

Question 49. An electron is in one of the 3d orbitals. Give the possible values on n, l, and mI for this electron.
Answer:

For 3d-subshell, n = 3,1 = 2  and m1 = -2, -1, 0, +1, +2.

Question 50. Give the number of electrons in the species +H2, H2, and.
Answer: The number of electrons present in +H2, H2, and 2O+ is 1, 2, and 15 respectively.

Question 51. Arrange falling radiations in increasing order of frequency; radiation from microwave own amber light from traffic signal radiation from FM radio cosmic ray from outer space X-rays.
Answer: Radiation from FM radio < microwave < amber light < Xrays < cosmic rays.

Question 52.  Write the possible values of’ m ‘ for a 4/-electron. 

Answer:

For a 4f-elcctron, n = 4, l = 3. Thus, the possible value of m will be: +3, +2, +1, 0, -1, -2, -3

Question 53. How many numbers of electrons are present in one HClO4 molecule?
Answer: In one molecule of HClO4molecule, total number of electrons present in it = (1 + 17 + 4 ×  8) = 50

Question 54. Explain why cathode rays are produced only at very low pressure of gas inside the discharge tube-
Answer: Gases being had conductor do not allow electricity to pass through them In discharge tube at high pressure.

Question 55. Mention two uses of cathode ray tubes in our daily life.
Answer: Television picture tube and fluorescent tube.

Question 56. Calculate the charge of 1 mol electron.
Answer: Charge Avogrado no, x Charge of 1 electron

⇒  (6.022 × 1023) × (1,602 ×10-19) =9.047 × 104C

Question 57. What happens when high-velocity cathode rays strike a tungsten foil?
Answer: X-rays are emitted.

Question 58. Who discovered the neutron?
Answer: J. Chadwick (1932).

Question 59.  Between proton or neutron which one is heavier?
Answer: Neutron (1.675× 10-24g) is slightly heavier than proton (1.6725× 10-24g).

Question 60. Name the experiment that helps us to determine the number of protons in the nucleus of an atom.
Answer: Moseley’s experiment on X-rays

Question 61. What is the relation between Cl and S2-?
Answer: Both have 18 electrons and hence, are isoelectronic

Question 62. Mention the most important application of the de Broglie concept.
Answer: The de-Broglie concept is utilized in the construction of an electron microscope used for the measurement of the size of very small objects.

Question 63. Identify the relation between the nuclides, 14Si38 & 15P31.
Answer: The number of neutrons in the nuclides is the same. Thus, they are isotones.

Question 64. A cation M3+ has 23 electrons. Find the atomic no. of M.
Answer: Number of electrons present in the neutral M-atom.

Question 65. Mention any three phenomena that can be explained with the help of the wave theory of light.
Answer: Interference, diffraction, polarisation.

Question 66. Differentiate between a quantum and a photon.
Answer:

The smallest packet of energy of any electromagnetic radiation is quantum and that of light is called a photon.

Question 67. Which property of electromagnetic radiation is useful in explaining the phenomena involving energy transfer?
Answer: Particle nature of electromagnetic radiation

Question 68. An electron beam hitting a ZnS screen produces scintillations on it What do you conclude?
Answer: From this phenomenon, we can conclude that electrons have a particle nature.

Question 69. An electron beam after hitting a nickel crystal produces a diffraction pattern. What do you conclude?
Answer: From this phenomenon, we can conclude that electrons have a particle nature.

Question 70. What type of spectrum will be obtained if the electron o/Hatom approaches its nucleus inspiral pathway?
Answer: A continuous spectrum will be obtained due to the constant emission of energy.

Question 71. Name the series of spectral lines observed in the visible region of the hydrogen spectrum.
Answer: Balmer series

Question 72. Which electronic transition corresponds to the third line in the Balmer series ofthe hydrogen spectrum?
Answer: Electronic transition from the 5th orbit to the 2nd orbit.

Question 73. Name the five series in the atomic spectrum of hydrogen.
Answer: Lyman, Balmer, Paschen, Brackett and Pfund.

Question 74. What is meant by the quantization energy of an electron?
Answer: This means that the electrons in an atom have only definite values of energy

Question 75. Mint is the value of Planck’s constant in the SI unit.
Answer: h = 6.626 × 10-34J-s

Question 76. Which theory forms the basis of Bohr’s atomic model?
Answer: Planck’s quantum theory.

Question 77. Who proposed the concept of the dual nature of electrons?
Answer: The concept was proposed by de Broglie.

Question 78. Whatare de Broglie waves?
Answer: The waves associated with matter particles in motion are called matter waves or de Broglie waves.

Question 79. Write de Broglie equation for microscopic particles.
Answer: \(\lambda=\frac{h}{p}\) wavelength p = momentum of particle (mv).

Question 80. What is the relation between wave nature and particle nature of moving particles?
Answer: Wave nature \(\propto \frac{1}{\text { particle nature }}\).

Question 81. For which particles is the uncertainty principle applicable?
Answer: Heisenberg’s uncertainty principle applies to tiny subatomic particles like electrons, protons, neutrons, etc.

Question 82. Write Schrodinger’s wave equation, indicating the significance ofthe notations used.
Answer: Schrodinger’s wave equation is based on the dual nature (wave and particle) of electrons.

Question 83. What is the basis of Schrodinger’s wave equation?
Answer: Schrodinger’s wave equation is based on the dual nature (wave and particle) of electrons.

Question 84. Schrodinger’s wave equation does not give us any idea about which quantum number.
Answer: Spin quantum number (s).

Question 85. How many nodal planes are present in 5d –orbital.
Answer: Number of nodal planes in 5d -orbital = 2

Question 86. Write the expression for radial distribution Junction.
Answer: RDF = 4π²r Ψ²

Question 87. Calculate the number of radial nodes and planar nodes in the 4dx²-y² orbital.
Answer:

No. of radial nodes =n-l-1 = 4-2-1 = 1

No. of planar nodes = l = 2

Question 88. What will be the sign of 2Ψ along an axis on the two opposite sides ofthe nucleus?
Answer: The sign of Ψ2p along an axis will be opposite on the two opposite sides ofthe nucleus

Question 89. What will be the values of Ψ2px2py, and Ψ2pz When the value of r=0?
Answer: When r = 0 , the value of Ψ2px2py  and Ψ2pz, is zero (0).

Question 90. In which direction the value of Ψdxy is zero?
Answer: Along the x,y, and z-axis

Question 91. In which direction the value of  dx²-y² is the highest?
Answer: Along the x and y-axis.

Question 92. How many angular nodes are present in dxy -orbital? Identify them.
Answer: Two angular nodes are present (xz -plane and yz -plane).

Question 93. In which direction is the value ofdÿ, is zero?
Answer: Along z -the z-axis.

Question 94. How many angular nodes are possible for an orbital?
Answer: ‘V number of angular nodes are possible (where Z = azimuthal quantum number).

Question 95. Does the number of angular nodes of an orbital depend on the principal quantum number?
Answer: No, it depends only on the azimuthal quantum number.

Question 96. How many angular nodes are present in s -s-orbital? Indicate the subshells present in the M -M-shell. How many orbitals are present in this shell?
Answer: s -orbital does not possess any angular nodes because the value of the angular wave function cannot be zero in any direction.

Question 97. How many quantum numbers are needed to designate an orbital? Name them.
Answer: Three quantum numbers are needed to designate an orbital, namely, ‘ n ‘ l’ and ‘ m

Question 98. Write the vdltt&Wfthe magnetic quantum number for the ‘3d ’-orbitals.
Answer: For 3d orbitals, 1 = 2. Hence the values of the magnetic quantum no., ‘ m’ are +2, +1, 0, -1, -2.

Question 99.4f-subshell of an atom contains 10 electrons. How many of Write the expression for the orbital angular momentum of a revolving electron.
Answer: The orbital angular momentum of the electron, ‘U is given by: L \(\sqrt{l(l+1)} \times \frac{h}{2 \pi}\)

Question 100. Write the expression for the orbital angular momentum of arevolving electron
Answer: The orbital angular momentum of an electron, ‘U is given by: I = \(\sqrt{l(l+1)} \times \frac{h}{2 \pi}.\)

Question 101. Why does an electron pair in an orbital have an opposite spin?
Answer: If a pair of electrons with parallel spin are present in the same orbital then they will repel each other.

Question 102. Balmer series of hydrogen spectrum lies in which region?
Answer: It lies in the visible region ofthe spectrum.

Question 103. How are the frequency and wave number of electromagnetic radiation related to each other?
Answer:

⇒ v=\(\frac{c}{\lambda}=c \times \frac{1}{\lambda}=c \times \bar{v}\)wave number \(\bar{v}=\frac{1}{\lambda}\)

Question 104. An electron beam after passing through a thin foil of gold produces a diffraction pattern (consisting of several concentric rings). What do you conclude?
Answer: Electron in motion has wage character.

Question 105. What is a quantum?
Answer: The smallest packet of energy of any radiation is called a quantum.

Question 106. What happens when an electron hits a zinc sulfide screen and what does it prove?
Answer: A scintillation is produced, which in turn proves that the electron has a particle nature.

Question 107. A scintillation is produced, which in turn proves that the electron has a particle nature.
Answer: [‘ m ‘ and ‘ e ‘ represent the mass and charge of the electron]

Question 108. Is Heisenberg’s uncertainty principle applicable to a stationary electron? Explain
Answer: It is not applicable. Since the velocity of a stationary electron is ‘zero’, (v = 0), its position can be located accurately.

Question 109. Name the series of spectral lines obtained, when electrons from various energy levels jump to the first orbit in hydrogen
Answer: Lyman series

Question 110. An atom of an element contains 29 electors and 35 n = 2, 1 = 1, neutrons. Deduce the number of protons and the electronic configuration of the element.
Answer: For an electrically neutral atom, the number of protons = the number of electrons = 29.

NCERT Solutions For Class 11 Chemistry Chapter 2 Structure Of Atom Fill In The Blanks

Question 1. The cgs unit of Planck’s constant is unit is _____________
Answer: Erg-s, J.s,

Question 2. The angular momentum of an electron in the nth orbit is _____________ 2+ ion.
Answer: nh/2π

Question 3. If an α -particle and two (i -particles are emitted from a radioactive element, the element produced becomes an _____________of the parent element.
Answer: Isotope

Question 4. With the help of Bohr’s atomic model, the idea of _____________quantum number was first obtained.
Answer: Principal

Question 5. Bohr’sunitatomic of Rydberg’smodel ignored constant _____________
Answer: Three-dimensional

Question 6. The unit of Rydergs’s Constant In CGS UNit is _____________
Answer: Cm-1

Question 7. The range of wavelength of visible light is _____________
Answer:  4000°-8000A°

Question 8. The ionization potential of hydrogen is _____________
Answer:  Cm-1

Question 9. Uhlenbeck and Goudsmit introduced the concept of_____________ quantum number.
Answer: 13.54eV

Question 10. The product of uncertainties in the position and momentum of an electron is always equal to or greater than_____________
Answer: Spin

Question 11. The product of uncertainties in the position and momentum of the electron is always equal to or greater than_____________
Answer: h/4n

Question 12. The number of magnetic quantum numbers required to describe the electrons of-subshell is _____________
Answer: 1. 12.5

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