Answer :
Ultraviolet light - (A) Given off by very hot objects, such as the sun
Gamma rays - (B) Given off by radioactive substances
Microwaves - (C) Used in radar and to heat food
X-rays - (D) Used in the medical field to see bone structure
Explanation :
Electromagnetic waves : It is a wave in which two vectors are vibrating mutually perpendicular to each other and in direction of the wave. The two vectors are electric field and magnetic field.
The gamma-rays, x-rays, ultraviolet-rays, infrared-rays, microwaves and radio-waves are the electromagnetic waves.
Ultraviolet light : It is a form of light that is not visible to the human eye. It is given off by very hot objects such as sun. The U.V light are harmful for living beings.
Gamma rays : It is arising from the radioactive decay of atomic nuclei. It has shortest wavelength waves and imparts high photon energy can pass through most forms of matters because they have no mass.
Microwaves : It is a wave having wavelength range 0.001-0.3 m is shorter than that of normal radio wave but greater than of infrared wave. It is used in the radar and to heat the food.
X-rays : It is a high energy wave and very short wavelength. It has ability to pass through many materials. It is used in the medical field to see the bone structure.
