NAUI NITROX DIVER FINAL EXAM
NEWEST 2026 ACTUAL EXAM TEST
BANK| COMPLETE 200 REAL EXAM
QUESTIONS AND CORRECT VERIFIED
ANSWERS/ ALREADY GRADED A+|
NAUI NITROX CERTIFICATION EXAM
PREP (MOST RECENT!!)
Q1. The main reason to dive with "nitrox" is to reduce
exposure to some of the problems in diving caused by:
A: Nitrogen
Rationale: Nitrox increases oxygen percentage, thereby reducing
the percentage of nitrogen inhaled. Lower nitrogen absorption
reduces decompression sickness risk.
Q2. We say that nitrogen is an inert gas. This means_____.
A: Our bodies do not use the nitrogen we breathe
Rationale: "Inert" in this context means physiologically inactive;
the body does not metabolize nitrogen.
,Q3. What is the primary safety hazard of breathing nitrogen
at depth?
A: Narcosis
Rationale: Nitrogen acts as an anesthetic at high partial pressures,
leading to impaired judgment (narcosis).
Q4. NAUI sanctioned enriched air nitrox training in:
A: 1992
Rationale: This is a historical date specific to NAUI's adoption of
the training standards.
Q5. Benefits of nitrox include:
A: Extended bottom time, Increased safety margins, Shorter
surface intervals
Rationale: Less nitrogen means longer no-decompression limits
(bottom time) and faster off-gassing (shorter surface intervals).
Q6. The greatest advantages for diving using nitrox occur in
what depth range?
A: 15-33 msw (50-110 fsw)
Rationale: In this "sweet spot," bottom time gains are maximized
without excessive oxygen toxicity risk.
Q7. True or False: A scuba diver breathing nitrox avoids any
risk of nitrogen narcosis.
A: False
Rationale: Nitrox reduces but does not eliminate narcosis, as
significant nitrogen remains in the mix.
,Q8. If a nitrox mix is 36% oxygen, what is the fraction of
oxygen in the gas mix?
A: 0.36
Rationale: Fraction = Percentage / 100 (36/100 = 0.36).
Q9. _____ describes the relationship between absolute pressure
and the volume of a gas.
A: Boyle's Law
Rationale: Boyle's Law states that at constant temperature,
pressure and volume are inversely related.
Q10. To find the partial pressure of a gas in a mixture:
A: Multiply the gas fraction by the absolute pressure
Rationale: This is Dalton's Law: Partial Pressure = Fraction ×
Absolute Pressure.
Q11. The water pressure plus atmospheric pressure equals:
A: Absolute pressure
Rationale: Gauge pressure (water) + Atmospheric pressure (1 ata)
= Absolute pressure.
Q12. What is the absolute pressure at 34 msw (111 fsw)?
A: 4.4 ata
Rationale: 34 msw / 10 msw per atm = 3.4 atm (water) + 1 atm
(air) = 4.4 ata.
Q13. What is the nitrogen partial pressure (PN2) in EAN35 at
a depth of 26 msw (85 fsw)?
, A: 2.3 ata
Rationale: EAN35 = 65% N2. Absolute pressure = 3.6 ata. PN2 =
0.65 × 3.6 = 2.34 ata .
Q14. What is the oxygen partial pressure (PO2) of EAN38 at
27 msw (87 fsw)?
A: 1.4 ata
Rationale: 27 msw = 3.7 ata abs. PO2 = 0.38 × 3.7 = 1.4 ata .
Q15. At what depth in the ocean is the absolute pressure 6.4
ata?
A: 54 msw (178 fsw)
Rationale: 6.4 ata total - 1 ata surface = 5.4 ata water pressure. 5.4
× 10 msw = 54 msw.
Q16. If the PO2 at 30 msw (98 fsw) is 1.4 atmospheres, what is
the oxygen fraction of the breathing mixture?
A: 0.35
Rationale: 30 msw = 4 ata. FO2 = 1. = 0.35 (35%) .
Q17. What is the partial pressure of nitrogen in air at 40 msw
(130 fsw)?
A: 3.9 ata
Rationale: Air = 79% N2. 40 msw = 5 ata. PN2 = 0.79 × 5 = 3.95
ata .
Q18. True or False. Narcosis is reduced significantly when
diving with enriched air nitrox.
NEWEST 2026 ACTUAL EXAM TEST
BANK| COMPLETE 200 REAL EXAM
QUESTIONS AND CORRECT VERIFIED
ANSWERS/ ALREADY GRADED A+|
NAUI NITROX CERTIFICATION EXAM
PREP (MOST RECENT!!)
Q1. The main reason to dive with "nitrox" is to reduce
exposure to some of the problems in diving caused by:
A: Nitrogen
Rationale: Nitrox increases oxygen percentage, thereby reducing
the percentage of nitrogen inhaled. Lower nitrogen absorption
reduces decompression sickness risk.
Q2. We say that nitrogen is an inert gas. This means_____.
A: Our bodies do not use the nitrogen we breathe
Rationale: "Inert" in this context means physiologically inactive;
the body does not metabolize nitrogen.
,Q3. What is the primary safety hazard of breathing nitrogen
at depth?
A: Narcosis
Rationale: Nitrogen acts as an anesthetic at high partial pressures,
leading to impaired judgment (narcosis).
Q4. NAUI sanctioned enriched air nitrox training in:
A: 1992
Rationale: This is a historical date specific to NAUI's adoption of
the training standards.
Q5. Benefits of nitrox include:
A: Extended bottom time, Increased safety margins, Shorter
surface intervals
Rationale: Less nitrogen means longer no-decompression limits
(bottom time) and faster off-gassing (shorter surface intervals).
Q6. The greatest advantages for diving using nitrox occur in
what depth range?
A: 15-33 msw (50-110 fsw)
Rationale: In this "sweet spot," bottom time gains are maximized
without excessive oxygen toxicity risk.
Q7. True or False: A scuba diver breathing nitrox avoids any
risk of nitrogen narcosis.
A: False
Rationale: Nitrox reduces but does not eliminate narcosis, as
significant nitrogen remains in the mix.
,Q8. If a nitrox mix is 36% oxygen, what is the fraction of
oxygen in the gas mix?
A: 0.36
Rationale: Fraction = Percentage / 100 (36/100 = 0.36).
Q9. _____ describes the relationship between absolute pressure
and the volume of a gas.
A: Boyle's Law
Rationale: Boyle's Law states that at constant temperature,
pressure and volume are inversely related.
Q10. To find the partial pressure of a gas in a mixture:
A: Multiply the gas fraction by the absolute pressure
Rationale: This is Dalton's Law: Partial Pressure = Fraction ×
Absolute Pressure.
Q11. The water pressure plus atmospheric pressure equals:
A: Absolute pressure
Rationale: Gauge pressure (water) + Atmospheric pressure (1 ata)
= Absolute pressure.
Q12. What is the absolute pressure at 34 msw (111 fsw)?
A: 4.4 ata
Rationale: 34 msw / 10 msw per atm = 3.4 atm (water) + 1 atm
(air) = 4.4 ata.
Q13. What is the nitrogen partial pressure (PN2) in EAN35 at
a depth of 26 msw (85 fsw)?
, A: 2.3 ata
Rationale: EAN35 = 65% N2. Absolute pressure = 3.6 ata. PN2 =
0.65 × 3.6 = 2.34 ata .
Q14. What is the oxygen partial pressure (PO2) of EAN38 at
27 msw (87 fsw)?
A: 1.4 ata
Rationale: 27 msw = 3.7 ata abs. PO2 = 0.38 × 3.7 = 1.4 ata .
Q15. At what depth in the ocean is the absolute pressure 6.4
ata?
A: 54 msw (178 fsw)
Rationale: 6.4 ata total - 1 ata surface = 5.4 ata water pressure. 5.4
× 10 msw = 54 msw.
Q16. If the PO2 at 30 msw (98 fsw) is 1.4 atmospheres, what is
the oxygen fraction of the breathing mixture?
A: 0.35
Rationale: 30 msw = 4 ata. FO2 = 1. = 0.35 (35%) .
Q17. What is the partial pressure of nitrogen in air at 40 msw
(130 fsw)?
A: 3.9 ata
Rationale: Air = 79% N2. 40 msw = 5 ata. PN2 = 0.79 × 5 = 3.95
ata .
Q18. True or False. Narcosis is reduced significantly when
diving with enriched air nitrox.
