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

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

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 

$$\begin{gathered} 1. {10}^2 \\ 2. 10 \\ 3. 50 \\ 4. 20 \end{gathered}$$

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

$$\begin{gathered} 1. 6.2 \times {10}^{-18} \\ 2. 5.6 \times {10}^{17} \\ 3. 6.2 \times {10}^{18} \\ 4. 32.2 \times {10}^{-20} \end{gathered}$$

The wavelength of the light emitted when the electron returns to the ground state in the H atom, from n = 5 to n = 1, would be: (The ground-state electron energy is –2.18 × 10^-18 j)
1. Wavelength = 9.498 x 10^-8 km
2. Wavelength = 12.498 x 10^-8 m
3. Wavelength = 9.498 x 10^-8 m
4. Wavelength = 9.498 x 10^-8 cm

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
$1. 7.17 \times {10}^{-19} {\mathrm{s}}^{-1}$
2. 4.13 × 10¹⁶ s^-1
3. 7.17 × 10¹⁹ s^-1
4. 1.26 × 10²⁰ s^-1

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

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

A radiation source emitted  2.5 × 10¹⁵ photons in 2 nanoseconds. Energy of the source is -

$$\begin{gathered} 1. 8.28 \times {10}^{-10} \mathrm{J} \\ 2. 8.24 \times {10}^{10} \mathrm{J} \\ 3. 7.12 \times {10}^{-11} \mathrm{J} \\ 4. 2.12 \times {10}^{ 10} \mathrm{J} \end{gathered}$$

Assertion: A black body is an ideal body that emits and absorbs radiation of all frequencies.

Reason: The frequency of radiation emitted by a body goes from lower frequency to a higher frequency with an increase in temperature.

1.  Both the assertion and the reason are true and the reason is the correct explanation of assertion.

2.  Both the assertion and the reason are true and the reason is not the correct explanation of assertion.

3.  The assertion is true but the reason is false.

4.  The assertion is false but the reason is true.

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