$TV$ waves range from . . . . . .

Match List-$I$ with List-$II$.

List-$I$	List-$II$
$(a)$ $10\, km$ height over earth's surface	$(i)$ Thermosphere
$(b)$ $70\, km$ height over earth's surface	$(ii)$ Mesosphere
$(c)$ $180\, km$ height over earth's surface	$(iii)$ Stratosphere
$(d)$ $270\, km$ height over earth's surface	$(iv)$ Troposphere

What is the use or importance of the ozone layer?

The waves having maximum wavelength among the following electromagnetic waves is

Match List-$I$ with List-$II$:

List-$I$ ($EM$ Wave)	List-$II$ (Wavelength Range)
$(A)$ Infrared	$(i)$ $ < 10^{-3} \, nm$
$(B)$ Ultraviolet	$(ii)$ $400 \, nm$ to $1 \, nm$
$(C)$ $X$-rays	$(iii)$ $1 \, mm$ to $700 \, nm$
$(D)$ Gamma rays	$(iv)$ $1 \, nm$ to $10^{-3} \, nm$

Choose the correct answer from the options given below:

Given below are some famous numbers associated with electromagnetic radiations in different contexts in physics. State the part of the electromagnetic spectrum to which each belongs.
$(a)$ $21 \; cm$ (wavelength emitted by atomic hydrogen in interstellar space).
$(b)$ $1057 \; MHz$ (frequency of radiation arising from two close energy levels in hydrogen; known as Lamb shift).
$(c)$ $2.7 \; K$ (temperature associated with the isotropic radiation filling all space; thought to be a relic of the 'big-bang' origin of the universe).
$(d)$ $5890 \; \mathring{A} - 5896 \; \mathring{A}$ (double lines of sodium).
$(e)$ $14.4 \; keV$ (energy of a particular transition in $^{57}Fe$ nucleus associated with a famous high-resolution spectroscopic method, Mossbauer spectroscopy).