NAUI NITROX CERTIFICATION ACTUAL EXAM 2025/2026
QUESTIONS AND VERIFIED ANSWERS.
What is the absolute pressure at 17 msw (56 fsw)?
2.7 ata
what is the oxygen partial pressure in EAN35 at a depth of 26 msw (85 fsw)?
1.3 ata
if the oxygen partial pressure in your mix is 1.3 ata at a depth of 37 msw (122
fsw), what is the fraction of oxygen in the mix?
0.28
The ______ in the air you are breathing limits the time you can stay at depth
nitrogen
in the early twentieth century, a quantitative model for nitrogen loading and dive
tables were developed by
John Scott Haldane
we say that nitrogen is an inert gas. this means
our bodies do not use the nitrogen we breathe
credit for developing and introducing nitrox diving techniques for standard scuba
goes to
Dr. Morgan Wells
NAUI sanctioned enriched air nitrox training in
1992
two benefits of diving with nitrox are
longer dive times and shorter surface intervals
what does the "x" stand for in the term EANx?
the percentage of oxygen in the mix
Page 1 of 7
, in 1878, Paul Bert established that_____, liberated as bubbles following sudden
decompression was the cause of decompression sickeness
nitrogen
nitrox is a _____ breathing gas
mid-range
nitrox provides the greatest advantages for dives in the _____ depth range
15-33 m (50-110 ft)
as a gas is heated in a rigid closed container its pressure will
increase
"if one quantity of gas will dissolve at one atmosphere of pressure, then three
quantities of gas will dissolve at three atmospheres." this statement refers to
which law?
Henry's Law
atmospheric pressure can be measured in many ways. what is one atmosphere in
millimeters of mercury?
760 mmHg
the ____ of a specific gas in a mix is the portion of the total pressure exerted by
that gas
partial pressure
what is the partial pressure of oxygen in air at a depth of 21 msw (69 fsw)?
0.65 ata
the symptoms of nitrogen narcosis parallel those often seen in
alcohol intoxication
____ law states: "at a constant temperature, the volume of a gas varies inversely
with absolute pressure, while the density of a gas varies directly with absolute
pressure."
Page 2 of 7
QUESTIONS AND VERIFIED ANSWERS.
What is the absolute pressure at 17 msw (56 fsw)?
2.7 ata
what is the oxygen partial pressure in EAN35 at a depth of 26 msw (85 fsw)?
1.3 ata
if the oxygen partial pressure in your mix is 1.3 ata at a depth of 37 msw (122
fsw), what is the fraction of oxygen in the mix?
0.28
The ______ in the air you are breathing limits the time you can stay at depth
nitrogen
in the early twentieth century, a quantitative model for nitrogen loading and dive
tables were developed by
John Scott Haldane
we say that nitrogen is an inert gas. this means
our bodies do not use the nitrogen we breathe
credit for developing and introducing nitrox diving techniques for standard scuba
goes to
Dr. Morgan Wells
NAUI sanctioned enriched air nitrox training in
1992
two benefits of diving with nitrox are
longer dive times and shorter surface intervals
what does the "x" stand for in the term EANx?
the percentage of oxygen in the mix
Page 1 of 7
, in 1878, Paul Bert established that_____, liberated as bubbles following sudden
decompression was the cause of decompression sickeness
nitrogen
nitrox is a _____ breathing gas
mid-range
nitrox provides the greatest advantages for dives in the _____ depth range
15-33 m (50-110 ft)
as a gas is heated in a rigid closed container its pressure will
increase
"if one quantity of gas will dissolve at one atmosphere of pressure, then three
quantities of gas will dissolve at three atmospheres." this statement refers to
which law?
Henry's Law
atmospheric pressure can be measured in many ways. what is one atmosphere in
millimeters of mercury?
760 mmHg
the ____ of a specific gas in a mix is the portion of the total pressure exerted by
that gas
partial pressure
what is the partial pressure of oxygen in air at a depth of 21 msw (69 fsw)?
0.65 ata
the symptoms of nitrogen narcosis parallel those often seen in
alcohol intoxication
____ law states: "at a constant temperature, the volume of a gas varies inversely
with absolute pressure, while the density of a gas varies directly with absolute
pressure."
Page 2 of 7
