If the electronic structure of oxygen atom is written as 1s2, 2s2  it would violate:

1. Hund's rule.

2. Paulis exclusion principle.

3. Both Hund's and Pauli's principles.

4. None of the above.

Subtopic:  Pauli's Exclusion Principle & Hund's Rule |
 74%
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Assertion (A): Bohr’s orbits are also called stationary states.
Reason (R): Electrons are stationary in an orbit.
 
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true but (R) is not the correct explanation of (A).
3. (A) is true but (R) is false.
4. (A) is false but (R) is true.

Subtopic:  Bohr's Theory |
 68%
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Assertion (A): In the third energy level, there is no f subshell.
Reason (R): For n = 3, the possible values of l are 0, 1, 2 and for f subshell l = 3.

1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true but (R) is not the correct explanation of (A).
3. (A) is true but (R) is false.
4. (A) is false but (R) is true.

Subtopic:  Shell & Subshell |
 78%
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Assertion (A):  The angular momentum of an electron in an atom is quantized.
Reason (R):  In an atom, only those orbits are permitted in which the angular momentum of the electron is a natural number multiple of h/2π.
 
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.
Subtopic:  Bohr's Theory |
 80%
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Assertion (A): The radius of the second orbit of He+ is equal to that of the first orbit of hydrogen.
Reason (R) The radius of an orbit in hydrogen-like species is directly proportional to n and inversely proportional to Z.

1. Both  (A) and (R) are True and (R) is the correct explanation of the (A).
2. Both (A) and (R) are True and (R) is not the correct explanation of the (A).
3.  (A) is True but (R) is False.
4. Both (A) and (R) are False.
Subtopic:  Bohr's Theory |
 70%
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Assertion (A): The number of radial nodes in 3 dz2  , is zero.
Reason (R): The number of angular nodes of atomic orbitals is equal to the value of l.
 
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.
Subtopic:  Nodal Plane |
 67%
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The ratio of the wavelengths of the last lines of the Balmer to Lyman series is

1. 4:1 2. 27:5
3. 3:1 4. 9:4
Subtopic:  Hydrogen Spectra |
 75%
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The mass and charge of one mole of electrons are, respectively:

1. 5.48 × 10-7 kg, 9.65 C, 
2. 5.48 × 10-7 C, 1.098 x 1027
3. 5.48 × 10-7 kg, 9.65 × 104 C
4. 9.65 × 104 C, 1.098 x 1027

Subtopic:  Number of Electron, Proton & Neutron |
 72%
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The maximum number of neutrons are present in the nuclei of:

1. O816
2. Mg1224
3. Fe2656
4. Sr3888

Subtopic:  Number of Electron, Proton & Neutron |
 92%
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The complete symbol for the atom with the given atomic number (Z) and atomic mass (A) would be, respectively :

i. Z = 17 , A = 35.
ii. Z = 92 , A = 233.
iii. Z = 4 , A = 9.


1.  Be49   U92233     Be49

2.  Cl1735    U92233    Be49

3.  Be49    Cl1735     U92233

4. U92233    Be49    Cl1735

Subtopic:  Number of Electron, Proton & Neutron |
 90%
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