Most Important Atomic Structure MCQs with Answers | Chemistry MCQs

The mass of a proton is:

9.1095 × 10⁻³¹ kg
1.602 × 10⁻²⁷ kg
1.6726 × 10⁻²⁷ kg
1.6750 × 10⁻²⁷ kg

What will be the effect on a proton when passed through an electric field?

Deflection towards the anode
Deflection perpendicular to the electric field
Deflection towards the cathode
Deflection downwards in the electric field

Positive rays are produced:

By burning of gas
By cooling of gas
By the bombardment of cathode rays on gas molecules
From the anode like cathode rays are produced from the cathode

The pressure in a gas discharge tube is kept at:

10 torr
1 torr
0.1 torr
0.01 torr

Positive rays give a flash on:

AgNO₃ plate
AgCl plate
ZnO
ZnS

The relationship between the energy of a photon of light and its frequency is given by:

de Broglie’s dual nature of matter
Planck’s Quantum Theory
Bohr’s model
Rutherford’s atomic model

The velocity of a photon:

Is independent of wavelength
Depends upon its source
Depends upon its frequency
Equals the square of its amplitude

Planck’s equation is:

E = mc²
E = mv²/2
E = hν
E = nℎ/2π

Planck’s theory states that energy is emitted:

In a continuous manner
In a discontinuous manner
Simultaneously
In the form of heat

Quantum number which is not derived from Schrodinger wave equation:

Principal
Azimuthal
Magnetic
Spin

A nodal plane in an orbital is the plane where electron density is:

Maximum
Zero
Infinite
Minimum

The number of degenerate orbitals in a sub-shell having sausage shape are

1
3
5
7

Quantum number values for the 3p orbital are:

n=3,ℓ=0
n=3,ℓ=1
n=2,ℓ=1
n=2,ℓ=0

The maximum number of electrons that can be accommodated in a p-subshell is:

2
6
10
14

Which sub-shell has the highest energy?

n=5,ℓ=3,m=+1
n=5,ℓ=2,m=+2
n=4,ℓ=3,m=0
n=4,ℓ=0,m=+1

Magnetic quantum number values for the d-subshell are

2
3
5
7

A p-orbital has ______ energy than an s-orbital of the same principal quantum number.

Lower
Higher
Equal
Variable from orbit to orbit

Which set of quantum numbers represents the 19th electron of a Cu atom?

n=4,ℓ=0,m=0,s=+1/2
n=3,ℓ=2,m=0,s=+1/2
n=4,ℓ=1,m=0,s=+1/2
n=3,ℓ=0,m=0,s=+1/2

The d-orbital which is bi-lobed with a collar is represented as:

d xy ​
d yz ​
d z2 ​
d x2−y2 ​

Which of the following species is/are isoelectronic with K+?

P⁻³
S⁻²
All of these
Si⁺⁴
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The atomic number of an element is 26. How many electrons are present in the M shell?

11
14
15
16

Which of the following ions has an electronic configuration similar to Ar?

Sc⁺²
Ti⁺⁴
Cr⁺²
Mn⁺⁶

In the electronic configuration of Cu and Cr, which of the following is true?

3d is fully filled
3d is half-filled
There are 7 electrons in s-orbitals
There are 8 electrons in s-orbitals

The total number of lobes in all the orbitals of a d-subshell are

2
16
4
18

"Two electrons in the same orbital should have opposite spins" according to

Aufbau's principal
Pauli's exclusion rule
Hund's rule
None of these

The e/m value for the canal rays is maximum for

Hydrogen
Nitrogen
Helium
Argon

Maximum numbers of electron in a sub-shell is given by

2(2ℓ-1)
2(2ℓ+1)
2(ℓ+1)
2ℓ+1

Which quantum number tells us about orientation of orbitals:

Principal quantum number
Spin quantum number
Azimuthal quantum number
Magnetic quantum number

The relative energies of 4s, 4p and 3d orbitals are in the order:

3d<4p<4s
3d<4s<4p
4s<3d<4p
4p<3d<4s

With increase in the value of principal quantum number 'n', the shape of the s-orbitals remain same although their sizes

Decrease
Remain the same
Increase
May or may not remain the same

Number of electrons in the outermost shell of chloride ion(Cl-) is

17
1
7
8

Correct order of energy in the given sub-shell is

5s>3d>3p>4s
3p>3d>5s>4s
5s>3d>4s>3p
3p>3d>4s>5s

According to the given number of protons, neutrons, and electrons, which option is correct? (MDCAT 2014)

ElementProtonsNeutronsElectrons
As334230
Ga313928
Ca202020
As³⁺, Ga³⁺, Ca
As³⁺, Ga³⁺, Ca²⁺
As³⁺, Ga²⁺, Ca
As³⁺, Ga, Ca²⁺

Which order is correct with respect to the increasing energy of orbitals? (MDCAT 2015)

4s < 4p < 4d < 4f
4s < 4d < 4p < 4f
4p < 4s < 4f < 4d
4f < 4s < 4d < 4p

Which one of the following pairs has the same electronic configuration as neon (Ne-10)? (MDCAT 2015)

Al³⁺, Cl⁻
Na⁺, Mg²⁺
K⁺, Cl⁻
Na⁺, F⁻

Number of neutrons in Zn (A=66, Z=30) is

30
38
35
36

The maximum number of electrons in an electronic configuration can be calculated by using the formula: (MDCAT 2016)

2n²
2n² + 2
2n² + 1
2l+1

The number of electrons in Ga³⁺ (Gallium ion) will be (A=71, Z=31): (MDCAT 2017)

28
29
30
34

Which of the following contains the same number of electrons and protons but different neutrons? (MDCAT 2017)

Isobars
Isotones
Isotopes
None of these

Which is the correct electronic configuration of Chromium (Cr, Z=24)? (MDCAT 2018)

1s² 2s² 2p⁶ 3s² 3p⁵ 4s² 3d⁴
1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵
1s² 2s² 2p⁶ 3s² 3p⁵ 3d⁶
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁴
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The maximum number of electrons in a sub-shell is given by: (NUMS 2019)

2(2l−1)
2(2l+1)
2(l+1)
2 l 2l

In potassium, the order of energy levels is:

3s > 3d
4s > 4p
4s < 3d
none of these

Which of the following elements in its atomic state has electrons filling first two spherically symmetrical orbitals? (SET 2019)

Hydrogen
Helium
Beryllium
Carbon

What are the values of principal quantum number and azimuthal quantum numbe for the last electron in Chlorine atom?

1, 6
3, 1
1, 3
6, 1 ​

The electron configuration for chromium is [Ar] 4s1 3d5.
Select the best explanation for this irregular electron configuration.

A half-filled d orbitals is slightly lower is energy than the 4 s , thus filling first.
The 4 s orbital is at a lower energy than the 3 d orbital, thus filling first.
Chromium is a transition metal and its electrons are loosely held.
d orbitals are dominant and shield electrons from orbitals close in energy.

The quantum number that describes the orientation of orbitals in three-dimensional space is: (ETEA 2019)

Spin quantum number
Azimuthal quantum number
Magnetic quantum number
Principal quantum number

Which of the following is the correct electronic configuration of Chromium (Cr, Z=24)? (MDCAT 2019)

[Ar] 3d4 4s2
[Ar] 3d6 4s0
[Ar] 3d5 4s1
[Ar] 3d3 4s2

The relationship between quantum numbers  and l is: (NMDCAT 2020)

n=l−1
l=n−2
l=n−1
n=l−2

Quantum number values for the ‘2p’ orbitals are: (NMDCAT 2020)

n=2,l=1
n = 1 , l = 2
n=1,l=0
n=2,l=0

 Which of the following pairs has one electron in its orbital? (NMDCAT 2020)

Li & Fe
Na & Cr
K & Mn
H & He

Which of the following has the lowest charge-to-mass (e/m) ratio? (NMDCAT 2020)

Li +2
He +
H +1
Be

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