The reason air has mass and can transmit sound waves while light does not have mass and does not require a medium to travel is rooted in the fundamental nature of these two phenomena: sound and light.
Sound is a mechanical wave, which means it propagates through the vibration of particles in a medium, such as air, water, or solids. When an object vibrates, it causes adjacent particles to vibrate, transferring the energy of the sound wave from one particle to another. In this process, the vibrating particles of the medium oscillate back and forth, creating compressions and rarefactions, which constitute the sound wave. Since sound requires a medium to travel, it can propagate through substances with mass, like air.
On the other hand, light is an electromagnetic wave. It consists of oscillating electric and magnetic fields that do not require a medium to propagate. These fields self-generate and propagate through space, including a vacuum. Light travels as a result of the interactions between electric and magnetic fields, following the principles of electromagnetism as described by Maxwell's equations. Unlike sound waves, light waves do not need particles to oscillate or a medium with mass to propagate.
In summary, sound waves rely on the physical movement of particles in a medium, such as air, which has mass. The mass of the medium allows sound to propagate. Light, being an electromagnetic wave, does not require a medium or mass for propagation. It can travel through empty space or vacuum without the need for particles to vibrate.