If the photon detector receives a total of 3.15$\times {10}^{-18}$ J from the radiation of 600 nm,
the number of photons received by the detector would be: 

$1.$ ${10}^2$
$2.$ $10$
$3.$ $50$
$4.$ $20$

If the velocity of the electron is 1.6 × 10⁶ ${\mathrm{ms}}^{-1}$. The de Broglie wavelength associated with this electron is:  

$1.$ $590$ $\mathrm{pm}$
$2.$ $455$ $\mathrm{pm}$
$3.$ $512$ $\mathrm{pm}$
$4.$ $401$ $\mathrm{pm}$

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

The wave number for the longest wavelength transition in the Balmer series of atomic hydrogen would be -
1. \(1 .   1 . 52   \times   \left(10\right)^{6}   m^{- 1}\)
2. \(2 .   3 . 14   \times   \left(10\right)^{6}   \left(cm\right)^{- 1}\)
3. \(3 .   15 . 2   \times   \left(10\right)^{6}   m^{- 1}\)
4. \(4 .   1 . 52   \times   \left(10\right)^{6}   \left(cm\right)^{- 1}\)

The wavelength of light emitted when the electron in a H atom undergoes the transition from an energy level with n = 4 to an energy level with n = 2, is :

1. 586 mm

2. 486 nm

3. 523 nm

4. 416 pm

A 25-watt bulb emits monochromatic yellow light with a wave length of 0.57µm. The rate of emission of quanta per second would be :

1. 7.17×10^-19 s^-1

2. 4.13×10¹⁶s-¹

3 . 7.17×10¹⁹ s^-1

4 . 1.26 ×10²⁰s^-1
${\mathrm{}}^{}$

If the electronic structure of oxygen atom is written as $1{\mathrm{s}}^2, 2{\mathrm{s}}^2$ it would violate:

1.  Hund's rule

2.  Paulis exclusion principle

3.  Both Hund's and Pauli's principles

4.  None of these