40. The inert gas which is substituted for nitrogen in the air used by deep sea divers for breathing, is A.Xenon B.Krypton C.Argon D.Helium
Answer: Option D Solution: Helium (He) is an inert gas that is less narcotic than nitrogen at equivalent pressure (in fact there is no evidence for any narcosis from helium at all), so it is more suitable for deeper dives than nitrogen. Helium is equally able to cause decompression sickness.
