NAUI NITROX DIVER FINAL EXAM NEWEST 2026
ACTUAL EXAM TEST BANK| COMPLETE 350 REAL
EXAM QUESTIONS AND CORRECT VERIFIED ANSWERS/
ALREADY GRADED A+| NAUI NITROX CERTIFICATION
EXAM PREP (MOST RECENT!!)
1. The main reason to dive with "nitrox" is to reduce exposure
to some of the problems in diving caused by _____.
Answer: Nitrogen
Rationale: Nitrox (Enriched Air Nitrox, EANx) reduces the
proportion of nitrogen in the breathing gas compared to
standard air (which is 79% nitrogen). By lowering nitrogen
absorption into body tissues, divers reduce their risk of
decompression sickness and nitrogen narcosis .
2. We say that nitrogen is an inert gas. This means _____.
Answer: Our bodies do not use the nitrogen we breathe
Rationale: An inert gas is one that is not metabolized by the
body. When we breathe nitrogen, it simply dissolves into our
1
,blood and tissues according to pressure and time (Henry's Law).
It plays no role in cellular metabolism or energy production .
3. What is the primary safety hazard of breathing nitrogen at
depth?
Answer: Narcosis
Rationale: The increased partial pressure of nitrogen at depth
causes nitrogen narcosis—a state of impaired judgment,
euphoria, and motor dysfunction similar to alcohol intoxication.
Narcosis becomes noticeable around 30 meters (100 feet) and
worsens with greater depth .
4. NAUI sanctioned enriched air nitrox training in _____.
Answer: 1992
Rationale: NAUI was a pioneer in recreational nitrox training,
officially sanctioning enriched air nitrox courses in 1992. This
made NAUI one of the first major recreational diver training
organizations to offer formal nitrox certification .
2
,5. Two benefits of diving with nitrox are _____.
Answer: Longer dive times and shorter surface intervals
Rationale: By reducing nitrogen absorption, nitrox extends no-
decompression limits (longer bottom time) on the first dive and
allows shorter surface intervals before subsequent dives. This
makes nitrox particularly valuable for repetitive diving and
multi-day dive trips .
6. Benefits of nitrox include (select all that apply):
Answer: Extended bottom time, Increased safety margins,
Shorter surface intervals
Rationale: All three are established benefits of using enriched
air nitrox. The reduced nitrogen load extends allowable bottom
time, increases safety margins by reducing DCS risk, and shortens
required surface intervals between dives .
7. The greatest advantages for diving using nitrox occur in
what depth range?
Answer: 15–33 msw (50–110 fsw)
3
, Rationale: This depth range provides the most significant
extension of no-decompression limits compared to air. Shallower
than 15 meters, bottom times are already long on air; deeper
than 33 meters, oxygen toxicity limits become restrictive. The
"sweet spot" for nitrox benefits is 50–110 feet .
8. True or False: A scuba diver breathing nitrox avoids any
risk of nitrogen narcosis.
Answer: False
Rationale: While nitrox reduces nitrogen intake, it does not
eliminate it. Even with EAN32 (32% oxygen, 68% nitrogen),
narcosis is still possible at sufficient depth. The reduction in
narcotic effect is only about 10–20%—noticeable but not
eliminative. Nitrox is not a narcosis-eliminating gas .
9. If a nitrox mix is 36% oxygen, what is the fraction of
oxygen in the gas mix?
Answer: 0.36
Rationale: To find the fraction of oxygen (FO₂), divide the
percentage by 100. Thus, 36% oxygen = 0.36 FO₂. This is the
4
ACTUAL EXAM TEST BANK| COMPLETE 350 REAL
EXAM QUESTIONS AND CORRECT VERIFIED ANSWERS/
ALREADY GRADED A+| NAUI NITROX CERTIFICATION
EXAM PREP (MOST RECENT!!)
1. The main reason to dive with "nitrox" is to reduce exposure
to some of the problems in diving caused by _____.
Answer: Nitrogen
Rationale: Nitrox (Enriched Air Nitrox, EANx) reduces the
proportion of nitrogen in the breathing gas compared to
standard air (which is 79% nitrogen). By lowering nitrogen
absorption into body tissues, divers reduce their risk of
decompression sickness and nitrogen narcosis .
2. We say that nitrogen is an inert gas. This means _____.
Answer: Our bodies do not use the nitrogen we breathe
Rationale: An inert gas is one that is not metabolized by the
body. When we breathe nitrogen, it simply dissolves into our
1
,blood and tissues according to pressure and time (Henry's Law).
It plays no role in cellular metabolism or energy production .
3. What is the primary safety hazard of breathing nitrogen at
depth?
Answer: Narcosis
Rationale: The increased partial pressure of nitrogen at depth
causes nitrogen narcosis—a state of impaired judgment,
euphoria, and motor dysfunction similar to alcohol intoxication.
Narcosis becomes noticeable around 30 meters (100 feet) and
worsens with greater depth .
4. NAUI sanctioned enriched air nitrox training in _____.
Answer: 1992
Rationale: NAUI was a pioneer in recreational nitrox training,
officially sanctioning enriched air nitrox courses in 1992. This
made NAUI one of the first major recreational diver training
organizations to offer formal nitrox certification .
2
,5. Two benefits of diving with nitrox are _____.
Answer: Longer dive times and shorter surface intervals
Rationale: By reducing nitrogen absorption, nitrox extends no-
decompression limits (longer bottom time) on the first dive and
allows shorter surface intervals before subsequent dives. This
makes nitrox particularly valuable for repetitive diving and
multi-day dive trips .
6. Benefits of nitrox include (select all that apply):
Answer: Extended bottom time, Increased safety margins,
Shorter surface intervals
Rationale: All three are established benefits of using enriched
air nitrox. The reduced nitrogen load extends allowable bottom
time, increases safety margins by reducing DCS risk, and shortens
required surface intervals between dives .
7. The greatest advantages for diving using nitrox occur in
what depth range?
Answer: 15–33 msw (50–110 fsw)
3
, Rationale: This depth range provides the most significant
extension of no-decompression limits compared to air. Shallower
than 15 meters, bottom times are already long on air; deeper
than 33 meters, oxygen toxicity limits become restrictive. The
"sweet spot" for nitrox benefits is 50–110 feet .
8. True or False: A scuba diver breathing nitrox avoids any
risk of nitrogen narcosis.
Answer: False
Rationale: While nitrox reduces nitrogen intake, it does not
eliminate it. Even with EAN32 (32% oxygen, 68% nitrogen),
narcosis is still possible at sufficient depth. The reduction in
narcotic effect is only about 10–20%—noticeable but not
eliminative. Nitrox is not a narcosis-eliminating gas .
9. If a nitrox mix is 36% oxygen, what is the fraction of
oxygen in the gas mix?
Answer: 0.36
Rationale: To find the fraction of oxygen (FO₂), divide the
percentage by 100. Thus, 36% oxygen = 0.36 FO₂. This is the
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