The de-Broglie wavelength of a particle having the momentum of
3.3 x 10^-24 kg m s^-1 will be;

1. 0.002 Å

2. 0.02 Å

3. 0.2 Å

4. 2Å

The wavelengths of two photons are 2000 Å and 4000 Å respectively. What is the ratio of their energies?

1. 1/4

2. 4

3. 1/2

4. 2

Which one of the following is not characteristic of Planck's quantum theory of radiation –

1. The energy is not absorbed or emitted in whole numbers or multiples of quantum.

2. Radiation is associated with energy.

3. Radiation energy is not emitted or absorbed continuously but in the form of small packets called quanta.

4. Magnitude of energy associated with a quantum is proportional to the frequency.

Calculate the energy in Joule corresponding to light of wavelength 45 nm : (Planck's

constant h = 6.63 x 10^-34 Js; speed of light c = 3 x 10⁸ ms^-1)

1. 6.67 x 10¹⁵                             

2. 6.67 x 10¹¹

3. 4.42 ^x10-15                             

4. 4.42 x 10^-18

Iodine molecule dissociates into atoms after absorbing light of 4500 $\stackrel{\circ }{A}$. If one quantum of radiation is absorbed by each molecule, calculate the kinetic energy of iodine atoms. Bond energy of I₂ is 240 kJ mol^-1.

1. $2.16\times {10}^{-20} J$

2. $0.16\times {10}^{-20} J$

3. $5.03\times {10}^{-20} J$

4. $8.32\times {10}^{-20} J$

The number of photons of light with a wavelength of 4000 pm that provide 1J of energy would be: 

$1.$ $2.01$ $\times$ ${10}^{16}$
$2.$ $2.01$ $\times$ ${10}^{19}$
$3.$ $4.14$ $\times$ ${10}^{23}$
$4.$ $2.14$ $\times$ ${10}^{21}$

Electromagnetic radiation of wavelength 242 nm is just sufficient to ionise sodium atom. The ionisation energy of sodium in kJ mol^–1 is :

1. 494

2. 4.94

3. 516

4. 0.50

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 × 10¹⁶ s^–1

3 . 7.17 × 10¹⁹ s^–1

4 . 1.26 × 10²⁰ s^–1
${\mathrm{}}^{}$

A nitrogen laser produces radiation at a wavelength of 337.1 nm. If the number of photons emitted per second is 5.6 × 10²⁴,
the power of the laser is:

$\mathrm{}$$1.$ $4.56$ $\times$ ${10}^7$ $\mathrm{J}$
$2.$ $3.33$ $\times$ ${10}^6$ $\mathrm{J}$
$3.$ $1.29$ $\times$ ${10}^6$ $\mathrm{J}$
$4.$ $9.17$ $\times$ ${10}^5$ $\mathrm{J}$