Chemistry Test 198

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Chemistry Test 198

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Weekly Quiz Competition

Question 1
4 / -1

Identify the incorrect statement from the following.

A
All the five 5d orbitals are different in size when compared to the respective 4d orbitals.

B
All the five 4d orbitals have shapes similar to the respective 3d orbitals.

C
In an atom, all the five 3d orbitals are equal in energy in free state.

D
The shapes of d_xy, d_yz and d_zx orbitals are similar to each other; and and are similar to each other.

Solution

In an atom, all the five 3d orbitals are equal in energy in free state i.e., degenerate.

- The size of orbital depends on principal quantum number ' n ' therefore all the five 3d orbitals are different in size when compared to the respective 4d orbitals.

- Shape of orbitals depends on azimuthal quantum number 'l' therefore shapes of 4d orbitals are similar to the respective 3d orbitals.
Question 2
4 / -1

Choose the correct answer from the options given below:

A
(A) - (iii), (B) - (iv), (C) - (ii), (D) - (i)

B
(A) - (iii), (B) - (iv), (C) - (i), (D) - (ii)

C
(A) - (iv), (B) - (iii), (C) - (i), (D) - (ii)

D
(A) - (iv), (B) - (iii), (C) - (ii), (D) - (i)

Solution

ℓ = 0 ⇒ s-subshell

ℓ = 1 ⇒ p-subshell

ℓ = 2 ⇒ d-subshell

ℓ = 3 ⇒ f-subshell

∴ n = 2, ℓ = 1 ⇒2p

n = 3, ℓ = 2 ⇒ 3d

n = 3, ℓ = 0 ⇒ 3s

n = 2, ℓ = 0 ⇒ 2s
Question 3
4 / -1

A particular station of All India Radio, New Delhi broadcasts on a frequency of 1,368 kHz (kilohertz). The wavelength of the electromagnetic radiation emitted by the transmitter is : [speed of light c = 3.0 × 10⁸ ms⁻¹]

A
219.3 m

B
219.2 m

C
2192 m

D
21.92 cm

Solution
Question 4
4 / -1

Which of the following series of transitions in the spectrum of hydrogen atom falls in visible region?

A
Brackett series

B
Lyman series

C
Balmer series

D
Paschen series

Solution

Lyman series : UV region

Balmer series : Visible region

Paschen series : IR region

Brackett series : IR region
Question 5
4 / -1

In hydrogen atom, the de Broglie wavelength of an electron in the second Bohr orbit is

[Given that Bohr radius, a₀ = 52.9pm]

A
211.6pm

B
211.6πpm

C
52.9πpm

D
105.8pm

Solution

Bohr radius, a₀ = 52.9pm

n = 2, r_n = n²a₀ = (2)²a₀= 4 × 52.9pm = 211.6pm

The angular momentum of an electron in a given stationary state can be expressed as in equation,
Question 6
4 / -1

Which one is the wrong statement?

A
The uncertainty principle is ∆E × ∆t ≥ h/4π

B
Half filled and fully filled orbitals have greater stability due to greater exchange energy, greater symmetry and more balanced arrangement.

C
The energy of 2s -orbital is less than he energy of 2p -orbital in case of hydrogen like atoms.

D
de-Broglie's wavelength is given by λ = h/mv, where m = mass of the particle, v = group velocity of the particle.

Solution

In case of hydrogen like atoms, energy depends on the principal quantum number only. Hence, 2s -orbital will have energy equal to 2p -orbital.
Question 7
4 / -1

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

A

B

C

D

Solution

orbitals have electron density along the axes while d_xy, d_yz and d_xz orbitals have electron density in between the axes.
Question 8
4 / -1

Which is the correct order of increasing energy of the listed orbitals in the atom of titanium

(At. no. Z = 22)

A
4s,3s,3p.3d

B
3s,3p,3d,4s

C
3s,3p,4s,3d

D
3s,4s,3p,3d

Solution

Ti(22) = 1s²2s²2p⁶3s²3p⁶4s²3d²

∴ Order of increasing energy is 3s,3p,4s,3d
Question 9
4 / -1

The number of d-electrons in Fe²⁺(Z = 26) is not equal to the number of electrons in which one of the following?

A
d- electrons in Fe (Z = 26)

B
p - electrons in Ne (Z = 10)

C
s- electrons in Mg (Z = 12)

D
p- electrons in Cl (Z = 17)
Solution
The number of d-electrons in Fe²⁺ is calculated by considering the electron configuration of neutral iron (Fe), which is [Ar] 3d⁶ 4s². Upon losing two electrons to form Fe²⁺, the configuration becomes [Ar] 3d⁶. Therefore, Fe²⁺ has 6 d-electrons.
- Option A: Neutral Fe has 6 d-electrons, which is equal to Fe²⁺'s d-electrons.
- Option B: Ne has 6 p-electrons, which is equal to Fe²⁺'s d-electrons.
- Option C: Mg has 2 s-electrons, which is not equal to Fe²⁺'s d-electrons.
- Option D: Cl has 5 p-electrons, which is not equal to Fe²⁺'s d-electrons.
Both options C and D have numbers of electrons that do not match the 6 d-electrons in Fe²⁺. However, since multiple-choice questions typically have one correct answer, option D is selected as it directly answers the question regarding p-electrons in Cl.
Question 10
4 / -1

Calculate the energy in Joule corresponding to light of wave length 45nm (Planck's constant h = 6.63 × 10⁻³⁴J s, speed of light, c = 3 × 10⁸ms⁻¹)

A
6.67 × 10¹⁵J

B
6.67 × 10¹¹J

C
4.42 × 10⁻¹⁵J

D
4.42 × 10⁻¹⁸J

Solution