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

A photon detector receives a total energy of \(3.15 \times 10^{-18}\) J from radiation with a wavelength of 600 nm. How many photons are received by the detector?

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

The energy associated with the emission of 2.5 × 10¹⁵ photons in 2 nanoseconds is:
1. \(8 . 28\) \(\times\) \(10^{- 10}\) \(J\)
2. \(8 . 24\) \(\times\) \(10^{11}\) \(J\)
3. \(7 . 12\) \(\times\) \(10^{- 11}\) \(J\)
4. \(2 . 12\) \(\times\) \(10^{-10}\)\(J\)

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 neon gas emits radiation of 616 nm. The number of quanta that are present in 2 J of energy is:

1. \(6.2 \times 10^{-18} \)
2. \(5.6 \times 10^{17} \)
3. \(6.2 \times 10^{18} \)
4. \(32.2 \times 10^{-20}\)