Which of the following gases is mixed with oxygen for breathing by divers in aqua lungs? A. Methane B. Nitrogen C. Helium D. Hydrogen

Methane
Nitrogen
Helium
Hydrogen

The correct answer is C. Helium.

Helium is mixed with oxygen for breathing by divers in aqua lungs because it is less dense than nitrogen, which reduces the risk of decompression sickness. Helium is also non-flammable, which makes it safer to use than other gases such as hydrogen.

Methane is a flammable gas that

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is not suitable for breathing. Nitrogen is the most abundant gas in the Earth’s atmosphere, but it can cause decompression sickness in divers if it is not mixed with other gases. Hydrogen is a flammable gas that is not suitable for breathing.