The gas used to dilute oxygen for breathing by deep sea divers is: A. Neon B. Argon C. Nitrogen D. Helium

The correct answer is D. Helium.

Helium is the gas used to dilute oxygen for breathing by deep sea divers. It is used because it is less dense than nitrogen, which helps to reduce the risk of decompression sickness. Helium is also non-toxic and does not cause narcosis, which are both risks associated with using nitrogen.

Neon, argon, and nitrogen are all gases that are used in various

applications, but they are not used to dilute oxygen for breathing by deep sea divers. Neon is a noble gas that is used in lighting and lasers. Argon is a noble gas that is used in welding and as a protective gas for arc welding. Nitrogen is a gas that is used in many industrial applications, such as fertilizer production and the manufacture of ammonia.

Helium is the best choice for diluting oxygen for breathing by deep sea divers because it is less dense than nitrogen, non-toxic, and does not cause narcosis.