The smallest wavelength of electromagnetic radiation is for

The correct answer is Option (4) → \( \gamma \) rays

In the electromagnetic spectrum, in order of decreasing wavelength: radio waves, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays.

    \( \text{Microwaves: about } 1\,\mathrm{mm} \text{ to } 0.1\,\mathrm{m} \)
    \( \text{Ultraviolet: about } 400\,\mathrm{nm} \text{ to } 1\,\mathrm{nm} \)
    \( \text{X-rays: about } 10\,\mathrm{nm} \text{ to } 10^{-4}\,\mathrm{nm} \)
    \( \gamma \text{ rays: less than about } 10^{-3}\,\mathrm{nm} \)

Gamma rays, produced in nuclear transitions, have the highest frequency and so the smallest wavelength.

NCERT (2026-27):
Summary – “… Different regions are known by different names; γ-rays, X-rays, ultraviolet rays, visible rays, infrared rays, microwaves and radio waves in order of increasing wavelength from 10^–2 Å or 10^–12 m to 10⁶ m.”