Which of the following electromagnetic waves are used in telecommunication?

An electromagnetic radiation has an energy of $14.4 \text{ keV}$. To which region of the electromagnetic spectrum does it belong?

$A$ source of power $4 \ kW$ emits $10^{20}$ photons in $1 \ s$. In which region of the electromagnetic spectrum does the emitted radiation lie?

The correct order of electromagnetic waves with increasing frequency is

Infrared rays can be detected by .......

The frequencies of $\gamma$-rays,$X$-rays,and ultraviolet radiations are $B, A,$ and $C$ respectively. Which of the following relations is correct?