Atomic Structure Test

Result

Atomic Structure Test - 19

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following is correct?

A
₁H¹ and ₂He³ are isotopes

B
₆C¹⁴ and ₇N¹⁴ are isotopes

C
₁₉K³⁹ and ₂₀Ca⁴⁰ are isotones

D
₉F¹⁹ and ₁₁Na²⁴ are isodiaphers

Solution

Because isotones means the same number of neutron, So, from the question, option c is right, number of neutron in k is,39-19= 20,and,the number of neutron in ca is also 40-20=20 so it is isotones.
Question 2
1 / -0

‘Hartree’ is the atomic unit of energy and is equal to

A
-13 .6 eV atom^-1

B
-27.2 eV atom ^-1

C
+13.6 eV atom ^-1

D
+27.2 eV atom^-1

Solution

The potential energy of an electron in the first Bohr’s orbit in the H-atom is

This energy is defined as an atomic unit of energy called HARTREE.
Question 3
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Wave number of a spectral line for a given transition is x cm^-1 for He⁺, then its value for Be³⁺ (isoelectronic of He⁺)for the same transition is

A
x cm^-1

B
4x cm^-1

C

D
2x cm^-1

Solution
Question 4
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Which of the following electronic transitions requires that the greatest quantity of energy be absorbed by a hydrogen atom ?

A
n = 1 to n = 2

B
n = 2 to n = 4

C
n = 3 to n = 6

D
n = 3 to n = ∞

Solution

Therefore, electronic transition (a) requires greatest quantity of energy.
Question 5
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An electron in H-atom in its ground state absorbs 1.5 times as much as energy as the minimum required for its escape from the atom
Q.
Thus, kinetic energy given to the emitted electron is

A
20.4 eV

B
34.0 eV

C
-20.4 eV

D
-34.0 eV

Solution

E₁ = Energy of H-atom in the ground state = 13.6 eV

Energy absorbed = (13.6 x 1.5) = 20.4 eV
E₂ = Energy of the excited state
= 13.6+ 20.4= 34.0 eV
ΔE = KE = (E₂ - E₁)
= 34.0 - 13.6 = 20.4 eV
Question 6
1 / -0

Ionisation energy of He⁺ is 19.6x10^-18 J atom ^-1. The energy of the first stationary state (n = 1)of Li²⁺ is

A
4.41 x 10^-16 J atom^-1

B
-4 .41 x 10^-17 J atom^-1

C
-2.20 x 10 ^-15J atom^-1

D
8. 82 x 10^-17J atom^-1

Solution

Ionisation energy = - Energy of the electron
Question 7
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The kinetic energy of an electron in the second Bohr orbit of a hydrogen atom is (a₀is Bohr radius)
[AIEEE 2012]

A

B

C

D

Solution

Also, angular momentum is quantised
Question 8
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Energy of the electron in nth orbit is given by E Wavelength of light required to excite an electron in an H-atom from level n = 1 to n = 2 will be (h = 6.62 x 10-³⁴ J s ; c = 3.0 x 10⁸ms ^-1)
[AIEEE 2012]

A
1.216x 10^-7 m

B
2.816x 10^-7 m

C
6.500x 10^-7 m

D
8.500x 10^-7 m

Solution

For H - atom , Z = 1
Question 9
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The potential energy of an electron in the second Bohr's orbit of the he±

A
- 54.4 eV

B
-13.6 eV

C
-108.8 eV

D
-27.2 eV

Solution
Question 10
1 / -0

In Lyman series, shortest wavelength of H-atom appears at x m, then longest wavelength in Balmer series of He⁺ appear at

A

B

C

D

Solution

For the spectral line in H -atom and H -like species (one electron)

For Lyman series
For shortest wavelength (maximum wave number) n₂ → ∞

For longest wave length (minimum wave number), n₂ = (n₁, + 1).
For Balmer series, n₁ = 2
Question 11
1 / -0

If the radius of the first Bohr orbit is x, then de-Broglie wavelength of the electron in the third orbit is nearly

A
2πx

B
6πx

C
9x

D
x/3

Solution

Angular momentum is quantised , hence