What is called as the electromagnetic spectrum?

Frequencies of various radiations are given as:
$v_v \rightarrow$ Visible light
$v_r \rightarrow$ Radio Wave
$v_{uv} \rightarrow$ Ultraviolet Waves
Then which of the following is true?

The frequency range from $3 \times 10^9 \, Hz$ to $3 \times 10^{10} \, Hz$ is known as:

Match List $I$ with List $II$ of electromagnetic waves with their corresponding wavelength ranges:

List $I$	List $II$
$(A)$ Microwave	$(I)$ $400\,nm$ to $1\,nm$
$(B)$ Ultraviolet	$(II)$ $1\,nm$ to $10^{-3}\,nm$
$(C)$ $X$-Ray	$(III)$ $1\,mm$ to $700\,nm$
$(D)$ Infra-red	$(IV)$ $0.1\,m$ to $1\,mm$

Choose the correct answer from the options given below:

What is the approximate wavelength range of the electromagnetic spectrum?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R.$
Assertion $A:$ $EM$ waves used for optical communication have longer wavelengths than that of microwaves employed in $RADAR$ technology.
Reason $R:$ Infrared $EM$ waves are more energetic than microwaves (used in $RADAR$).
In the light of the given statements,choose the correct answer from the options given below: