Tamil Nadu Board of Secondary EducationHSC Science Class 11th

# Tamil Nadu Board Samacheer Kalvi solutions for Class 11th Chemistry Volume 1 and 2 Answers Guide chapter 2 - Quantum Mechanical Model of Atom [Latest edition]

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## Chapter 2: Quantum Mechanical Model of Atom

Evaluation
Evaluation [Pages 60 - 66]

### Tamil Nadu Board Samacheer Kalvi solutions for Class 11th Chemistry Volume 1 and 2 Answers Guide Chapter 2 Quantum Mechanical Model of Atom Evaluation [Pages 60 - 66]

#### Choose the best answer

Evaluation | Q I. 1. | Page 60

Electronic configuration of species M2+ is 1s2 2s2 2p6 3s2 3p6 3d6 and its atomic weight is 56. The number of neutrons in the nucleus of species M is

• 26

• 22

• 30

• 24

Evaluation | Q I. 2. | Page 60

The energy of light of wavelength 45 nm is

• 6.67 × 1015J

• 6.67 × 1011J

• 4.42 × 10–18J

• 4.42 × 10–15J

Evaluation | Q I. 3. | Page 60

The energies E1 and E2 of the two radiations are 25 eV and 50 eV respectively. The relation between their wavelengths ie λ1 and λ2 will be

• λ_1/λ_2 = 1

• λ1 = 2λ2

• λ1 = sqrt(25 xx 50) λ2

• 1 = λ2

Evaluation | Q I. 4. | Page 60

Splitting of spectral lines in an electric field is called __________.

• Zeeman effect

• Shielding effect

• Compton effect

• Stark effect

Evaluation | Q I. 5. | Page 60

Based on equation E = -2.178 xx 10^(-18) "J" ("z"^2/"n"^2), certain conclusions are written. Which of them is not correct?

• Equation can be used to calculate the change in energy when the electron changes orbit.

• For n = 1, the electron has a more negative energy than it does for n = 6 which means that the electron is more loosely bound in the smallest allowed orbit.

• The negative sign in equation simply means that the energy of electron bound to the nucleus is lower than it would be if the electrons were at the infinite distance from the nucleus.

• Larger the value of n, the larger is the orbit radius.

Evaluation | Q I. 6. | Page 60

According to the Bohr Theory, which of the following transitions in the hydrogen atom will give rise to the least energetic photon?

• n = 6 to n = 1

• n = 5 to n = 4

• n = 5 to n = 3

• n = 6 to n = 5

Evaluation | Q I. 7. | Page 61

Assertion: The spectrum of He+ is expected to be similar to that of hydrogen.

Reason: He+ is also one electron system.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Evaluation | Q I. 8. | Page 61

Which of the following pairs of d-orbitals will have electron density along the axes?

• "d"_("z"^2), "d"_"xz"

• "d"_"xz", "d"_"yz"

• "d"_("z"^2), "d"_("x"^2-"y"^2)

• "d"_"xy", "d"_("x"^2-"y"^2)

Evaluation | Q I. 9. | Page 61

Two electrons occupying the same orbital are distinguished by __________.

• azimuthal quantum number

• spin quantum number

• magnetic quantum number

• orbital quantum number

Evaluation | Q I. 10. | Page 61

The electronic configuration of Eu (Atomic no. 63) Gd (Atomic no. 64) and Tb (Atomic no. 65) are

• [Xe] 4f6 5d1 6s2, [Xe] 4f7 5d1 6s2 and [Xe] 4f8 5d1 6s2

• [Xe] 4f7 6s2, [Xe] 4f7 5d1 6s2 and [Xe] 4f9 6s2

• [Xe] 4f7 6s2, [Xe] 4f8 6s2 and [Xe] 4f8 5d1 6s2

• [Xe] 4f6 5d1 6s2, [Xe] 4f7 5d1 6s2 and [Xe] 4f9 6s2

Evaluation | Q I. 11. | Page 61

The maximum number of electrons in a sub shell is given by the expression

• 2n2

• 2l + 1

• 4l + 2

• none of these

Evaluation | Q I. 12. | Page 61

For d-electron, the orbital angular momentum is

• (sqrt2"h")/(2π)

• sqrt(2"h")/(2π)

• (sqrt(2 xx 4)"h")/(2π)

• (sqrt6"h")/(2π)

Evaluation | Q I. 13. | Page 62

What is the maximum numbers of electrons that can be associated with the following set of quantum numbers?

n = 3, l = 1 and m = –1

• 4

• 6

• 2

• 10

Evaluation | Q I. 14. | Page 62

Assertion: Number of radial and angular nodes for 3p orbital are 1, 1 respectively.

Reason: Number of radial and angular nodes depends only on principal quantum number.

• both assertion and reason are true and reason is the correct explanation of assertion.

• both assertion and reason are true but reason is not the correct explanation of assertion.

• assertion is true but reason is false.

• both assertion and reason are false.

Evaluation | Q I. 15. | Page 62

The total number of orbitals associated with the principal quantum number n = 3 is

• 9

• 8

• 5

• 7

Evaluation | Q I. 16. | Page 62

If n = 6, the correct sequence for filling of electrons will be,

• ns → (n – 2)f → (n – 1)d → np

• ns → (n – 1)d → (n – 2)f → np

• ns → (n – 2)f → np → (n – 1)d

• none of these are correct

Evaluation | Q I. 17. | Page 63

Consider the following sets of quantum numbers:

 n l m s (i) 3 0 0 +1/2 (ii) 2 2 1 -1/2 (iii) 4 3 –2 +1/2 (iv) 1 0 –1 +1/2 (v) 3 4 3 -1/2

Which of the following sets of quantum number is not possible?

• (i), (ii), (iii) and (iv)

• (ii), (iv) and (v)

• (i) and (iii)

• (ii), (iii) and (iv)

Evaluation | Q I. 18. | Page 63

How many electrons in an atom with atomic number 105 can have (n + 1) = 8?

• 30

• 17

• 15

• unpredictable

Evaluation | Q I. 19. | Page 63

Electron density in the yz plane of 3dxy orbital is

• zero

• 0.50

• 0.75

• 0.90

Evaluation | Q I. 20. | Page 63

If uncertainty in position and momentum are equal, then minimum uncertainty in velocity is

• 1/"m" sqrt("h"/π)

• sqrt("h"/π)

• 1/"2m" sqrt("h"/π)

• "h"/(4π)

Evaluation | Q I. 21. | Page 63

A macroscopic particle of mass 100 g and moving at a velocity of 100 cm s–1 will have a de Broglie wavelength of

• 6.6 × 10–29 cm

• 6.6 × 10–30 cm

• 6.6 × 10–31 cm

• 6.6 × 10–32 cm

Evaluation | Q I. 22. | Page 63

The ratio of de Broglie wavelengths of a deuterium atom to that of an α - particle, when the velocity of the former is five times greater than that of later, is

• 4

• 0.2

• 2.5

• 0.4

Evaluation | Q I. 23. | Page 63

The energy of an electron in the 3rd orbit of hydrogen atom is –E. The energy of an electron in the first orbit will be

• –3E

• (-"E")/3

• (-"E")/9

• –9E

Evaluation | Q I. 24. | Page 63

Time independent Schrodinger wave equation is

• hat"H" ψ = "E"ψ

• ∇^2ψ + (8π^2"m")/"h"^2 ("E + V")ψ = 0

• (∂^2ψ)/(∂"x"^2) + (∂^2ψ)/(∂"y"^2) + (∂^2ψ)/(∂"z"^2) + (2"m")/"h"^2 ("E" - "V")ψ = 0

• all of these

Evaluation | Q I. 25. | Page 63

Which of the following does not represent the mathematical expression for the Heisenberg uncertainty principle?

• Δ"x".Δ"p" ≥"h"/(4π)

• Δ"x".Δ"v" ≥"h"/(4π"m")

• Δ"E".Δ"t" ≥"h"/(4π)

• Δ"E".Δ"x" ≥"h"/(4π)

#### Write brief answer to the following questions

Evaluation | Q II. 1. | Page 64

Which quantum number reveal information about the shape, energy, orientation and size of orbitals?

Evaluation | Q II. 2. | Page 64

How many orbitals are possible for n = 4?

Evaluation | Q II. 3. | Page 64

How many radial nodes for 2s, 4p, 5d and 4f orbitals exhibit? How many angular nodes?

Evaluation | Q II. 4. | Page 64

The stabilisation of a half-filled d-orbital is more pronounced than that of the p-orbital why?

Evaluation | Q II. 5. | Page 64

Consider the following electronic arrangements for the d5 configuration.

 ⥮ ⥮ 1 (a)

 1 1 1 ⥮ (b)

 1 1 1 1 1 (c)
1. which of these represents the ground state.
2. which configuration has the maximum exchange energy.
Evaluation | Q II. 6. | Page 64

State and explain Pauli's exclusion principle.

Evaluation | Q II. 7. a. | Page 64

Define orbital?

Evaluation | Q II. 7. b. | Page 64

what are the n and l values for 3px and "4d"_("x"^2 - "y"^2) electron?

Evaluation | Q II. 8. | Page 64

Explain briefly the time independent Schrodinger wave equation?

Evaluation | Q II. 9. | Page 64

Calculate the uncertainty in position of an electron, if Δv = 0.1% and υ = 2.2 × 106 ms-1

Evaluation | Q II. 10. | Page 64

Determine the values of all the four quantum numbers of the 8th electron in the O-atom and 15th electron in Cl atom.

Evaluation | Q II. 11. | Page 64

The quantum mechanical treatment of the hydrogen atom gives the energy value:

En = (-13.6)/"n"^2 ev atom−1

1. use this expression to find ΔE between n = 3 and n = 4
2. Calculate the wavelength corresponding to the above transition.
Evaluation | Q II. 12. | Page 65

How fast must a 54 g tennis ball travel in order to have a de Broglie wavelength that is equal to that of a photon of green light 5400 Å?

Evaluation | Q II. 13. | Page 65

For each of the following, give the sub level designation, the allowable m values and the number of orbitals

1. n = 4, l = 2
2. n = 5, l = 3
3. n = 7, l = 0
Evaluation | Q II. 14. | Page 65

Give the electronic configuration of Mn2+ and Cr3+

Evaluation | Q II. 15. | Page 65

Describe the Aufbau principle.

Evaluation | Q II. 16. | Page 65

An atom of an element contains 35 electrons and 45 neutrons. Deduce

1. the number of protons
2. the electronic configuration for the element
3. All the four quantum numbers for the last electron
Evaluation | Q II. 17. | Page 65

Show that the circumference of the Bohr orbit for the hydrogen atom is an integral multiple of the de Broglie wavelength associated with the electron revolving around the nucleus.

Evaluation | Q II. 18. | Page 65

Calculate the energy required for the process.

$\ce{He^+_{(g)} -> He^2+_{(g)} + e^-}$

The ionisation energy for the H atom in its ground state is −13.6 ev atom−1.

Evaluation | Q II. 19. | Page 65

An ion with mass number 37 possesses unit negative charge. If the ion contains 11.1% more neutrons than electrons. Find the symbol of the ion.

Evaluation | Q II. 20. | Page 65

The Li2+ ion is a hydrogen like ion that can be described by the Bohr model. Calculate the Bohr radius of the third orbit and calculate the energy of an electron in 4th orbit.

Evaluation | Q II. 21. | Page 65

Protons can be accelerated in particle accelerators. Calculate the wavelength (in Å) of such accelerated proton moving at 2.85 × 108 ms−1 (the mass of proton is 1.673 × 10−27 Kg).

Evaluation | Q II. 22. | Page 65

What is the de Broglie wavelength (in cm) of a 160 g cricket ball travelling at 140 Km hr−1?

Evaluation | Q II. 23. | Page 66

Suppose that the uncertainty in determining the position of an electron in an orbit is 0.6 Å. What is the uncertainty in its momentum?

Evaluation | Q II. 24. | Page 66

Show that if the measurement of the uncertainty in the location of the particle is equal to its de Broglie wavelength, the minimum uncertainty in its velocity (ΔV) is equal to 1/4π of its velocity (V).

Evaluation | Q II. 25. | Page 66

What is the de Broglie wavelength of an electron, which is accelerated from the rest, through a potential difference of 100V?

Evaluation | Q II. 26. | Page 66

Identify the missing quantum numbers and the sub energy level

 n l m Sub energy level ? ? 0 4d 3 1 0 ? ? ? ? 5p ? ? −2 3d
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Evaluation

## Tamil Nadu Board Samacheer Kalvi solutions for Class 11th Chemistry Volume 1 and 2 Answers Guide chapter 2 - Quantum Mechanical Model of Atom

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Concepts covered in Class 11th Chemistry Volume 1 and 2 Answers Guide chapter 2 Quantum Mechanical Model of Atom are Introduction to Atom Models, Wave Particle Duality of Matter, Heisenberg’s Uncertainty Principle, Quantum Mechanical Model of Atom – SchröDinger Equation, Quantum Numbers, Filling of Orbitals.

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