Which of the following particles can travel the longest distance in air?

Gamma rays can travel the longest distance in air among the particles listed. This is primarily due to their nature as high-energy electromagnetic radiation. Gamma rays do not carry any mass or charge, allowing them to penetrate materials, including air, more effectively than other forms of radiation.

In contrast, alpha particles are heavy and positively charged, which causes them to interact more readily with matter, resulting in a very short range—typically only a few centimeters in air. Beta particles, being lighter and charged (but still far heavier than gamma rays), have a greater range than alpha particles but still do not approach the distances that gamma rays can travel. Neutrons, while uncharged and capable of traveling longer distances than alpha and beta particles, can still be significantly slowed down or absorbed by collisions with air molecules, limiting their effective range compared to gamma rays.

Thus, gamma rays stand out as the particles capable of traveling the farthest in air due to their lack of mass and charge and their ability to maintain high energy over longer distances.