Electromagnetic radiation with maximum wavelength is:
A. Ultraviolet
B. Radio Waves
C. X- rays
D. Infrared

Hint: Electromagnetic radiation relates to the electromagnetic spectrum that consists of all types of radiation. The radiations are differentiated on the basis of frequencies, wavelengths, and photon energies. The radiation with maximum wavelength could be known as wavelength is inversely proportional to the frequency.

Complete step by step answer:
-First, let us know about the electromagnetic spectrum. As mentioned it consists of electromagnetic radiations, i.e. radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, gamma rays, and cosmic rays. It represents the decreasing order of wavelength, and increasing order of frequencies.
-Now, if we talk about the options, the first option is ultraviolet rays. In the electromagnetic spectrum the wavelength lies between the range of 400nm to 1nm.
-The second option is radio waves, the wavelength lies in the range > 1mm.
-The third option is X-rays; its wavelength lies in the range of 1nm – 4nm.
-The fourth option is infrared radiation; its wavelength lies in the range of 25 micrometer to 2.5 micrometer.
In the last, we can conclude that the electromagnetic radiation with the maximum wavelength is radio waves.
Hence, the correct option is (B).

Additional information: Radio waves are used for TV, or mobile communication. The emission of radio waves is from the gases and stars in space. The main source of ultraviolet radiation is the sun.

Note: Don’t get confused between the different ranges of wavelengths. The radio waves have maximum wavelength, and have the minimum frequency. You must remember the sequence of radiations in the spectrum.