$A$ 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 match between the entries in column $I$ and column $II$ is:
$I$ (Radiation) | $II$ (Wavelength)
$(a)$ Microwave | $(i)$ $100 \, m$
$(b)$ Gamma rays | $(ii)$ $10^{-15} \, m$
$(c)$ $A.M.$ radio waves | $(iii)$ $10^{-10} \, m$
$(d)$ $X$-rays | $(iv)$ $10^{-3} \, m$

In which one of the following regions of the electromagnetic spectrum will the vibrational motion of molecules give rise to absorption?

Which of the following rays has the maximum frequency?

Arrange the following in the ascending order of wavelength $(\lambda) :$
$(A)$ Microwaves $(\lambda_1)$
$(B)$ Ultraviolet rays $(\lambda_2)$
$(C)$ Infrared rays $(\lambda_3)$
$(D)$ $X-$rays $(\lambda_4)$
Choose the most appropriate answer from the options given below $:-$

The device used to detect infrared radiations is