Gases mix properly without any mechanical aid.

Explanation:
Gases have the unique property of being able to mix with each other easily and quickly. This is due to the random motion of gas particles, also known as Brownian motion. The process of gas mixing is governed by several factors, including diffusion and the kinetic theory of gases.

Diffusion:
Diffusion is the process by which gas particles spread out and mix with each other. It occurs due to the random motion of the gas particles. When two or more gases are in close proximity, their particles collide with each other and exchange momentum. These collisions cause the gas particles to spread out and mix, leading to a uniform distribution of the gases.

Kinetic Theory of Gases:
The kinetic theory of gases explains the behavior of gas particles. According to this theory, gas particles are in constant motion and have high kinetic energy. They move in straight lines until they collide with each other or the walls of the container. These collisions transfer energy and momentum between the particles, causing them to mix and distribute evenly throughout the container.

Random Motion:
The random motion of gas particles plays a crucial role in the mixing process. The particles move in all directions with different velocities, resulting in a chaotic motion. As a result, gas particles quickly spread out and fill the available space, leading to a homogeneous mixture.

Conclusion:
In summary, gases mix properly without any mechanical aid due to the process of diffusion and the random motion of gas particles. The kinetic theory of gases explains the behavior of gas particles and their ability to mix with each other. This property of gases is essential in various applications, such as air pollution control, gas exchange in the respiratory system, and chemical reactions in the atmosphere.