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.

If the electronic structure of oxygen atom is written as $1{\mathrm{s}}^2,<mspace\; width="1em"></mspace>2{\mathrm{s}}^2$  it would violate:

1. Hund's rule.

2. Paulis exclusion principle.

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

4. None of the above.

The ratio of the wavelengths of the last lines of the Balmer to Lyman series is

The maximum number of neutrons are present in the nuclei of:
1. \(_8^{16}\mathrm{O}\)
2. \(_{12}^{24}\mathrm{Mg}\)
3.\(_{26}^{56}\mathrm{Fe}\)
4. \(_{38}^{88}\mathrm{Sr}\)

Yellow light emitted from a sodium lamp has a wavelength (λ) of 580 nm. The frequency (ν) and wave number of this yellow light would be, respectively:

1. 517 × 10¹⁴ s^–1 , 172 × 10⁶ m^–1

2. 6.17 × 10¹⁴ s^–1 , 1.72 × 10⁶ m^–1

3. 4.17 × 10¹⁴ s^–1 , 2.72 × 10⁶ m^–1

4. 5.17 × 10¹⁴ s^–1 , 1.72 × 10⁶ m^–1

The energy of the photon with a frequency of 3 × 10¹⁵ Hz is:

1. 1.988 × ${10}^{-18}$ J
2. 1.588 × ${10}^{-18}$ J
3. 1.288 × ${10}^{-18}$ J
4. 2.988 × ${10}^{-18}$ J

A photon of wavelength 4 × 10^–7 m strikes a metal surface, the work function of the metal being 2.13 eV.  The kinetic energy of emission would be:

The possible values of n, l, and m for the electron present in 3d would be respectively:

1. n = 3, l = 1, m = – 2, – 1, 3, 1, 2

2. n = 3, l = 3, m = – 2, – 1, 0, 1, 2

3. n = 3, l = 2, m = – 2, – 1, 0, 1, 2

4. n = 5, l = 2, m = – 2, – 1, 0, 1, 2

A certain particle carries 2.5 × 10^–16 C of static electric charge. The number of electrons present in it would be: