An atom emits energy equal to $4 \times 10^{-12} \, erg$. To which part of the electromagnetic spectrum does it belong?

The laser in an audio compact disc uses light of wavelength $7.8 \times 10^2 \ nm$. What is the frequency of light emitted by the laser?

Electromagnetic radiations of frequency $\nu$ consist of a stream of particles called photons. Which of the following statements is / are true about photons:

Which one of the following frequencies of radiation (in $Hz$) has a wavelength of $600 \ nm$?

What is interference in the context of electromagnetic radiation?

$a$,$b$,$c$,$d$ are electromagnetic radiations. Frequencies of $a$,$b$ are $3 \times 10^{15} \ Hz$,$2 \times 10^{14} \ Hz$,respectively,whereas wavelengths of $c$,$d$ are $400 \ nm$,$750 \ nm$,respectively. The increasing order of their energies is