Gamma rays x rays visible light and radio waves are all types of

Electromagnetic waves

Explanation:

Electromagnetic waves are waves that consist of oscillating electric and magnetic fields, that oscillate perpendicularly to each other and perpendicularly to the direction of propagation of the wave (for such a reason, these waves are also called transverse waves).

Electromagnetic waves always travel in a vacuum at the same speed, called speed of light:

and they are classified into 7 different types, according to their frequency. From lowest to highest frequency, we have:

Radio waves

Microwaves

Infrared

Visible light

Ultraviolet

X-rays

Gamma rays

Therefore, gamma rays, x-rays, visible light and radio waves are all types of electromagnetic waves with different frequencies.

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.