The power of a source is $4 \, kW$. If it produces $10^{20}$ photons in $1 \, s$,then the radiation emitted from this source belongs to which part of the electromagnetic spectrum?

Match the electromagnetic radiations given in List-$I$ with their uses given in List-$II$.
| List-$I$ | List-$II$ |
| :--- | :--- |
| $A$) $X$-rays | $P$) Remote switches |
| $B$) $UV$-rays | $Q$) Finger prints in forensic labs |
| $C$) Radio waves | $R$) Crystal structure study |
| $D$) $IR$-rays | $S$) $TV$ communication system |

Match List-$I$ (Wavelength range of electromagnetic spectrum) with List-$II$ (Method of production of these waves) and select the correct option from the options given below the lists:

List-$I$	List-$II$
$(1)$ $700\, nm$ to $1\, mm$	$(i)$ Vibration of atoms and molecules
$(2)$ $1\, nm$ to $400\, nm$	$(ii)$ Inner shell electrons in atoms moving from one energy level to a lower level
$(3)$ $< 10^{-3}\, nm$	$(iii)$ Radioactive decay of the nucleus
$(4)$ $1\, mm$ to $0.1\, m$	$(iv)$ Magnetron valve

Which of the following groups of electromagnetic waves is in increasing order of frequency?

The approximate height of the ozone layer above the ground is:

Fingerprints on a piece of paper may be detected by sprinkling fluorescent powder on the paper and then looking at it under: