Scientific Diving: Nitrox Practice
Problems. Questions with Correct
Verified Answers. Latest 2026-2027.
Graded A
A common misconception is, that compared to air, Nitrox enables Divers to
dive:
A. deeper
B. longer
C. shorter
D. more shallow - ANSA. deeper
According to the SSI CNS Clock table you have two different CNS Clock
limits. One for a single dive, and one for a 24 hr period. These limits are
for an ppO2 of 1.4 bar:
A. 180 mins single dive / 210 mins 24 hrs
B. 150 mins single dive / 180 mins 24 hrs
C. 120 mins single dive/ 180 mins 24 hrs
D. 180 mins single dive/ 120 mins 24 hrs - ANSB. 150 mins single dive /
180 mins 24 hrs
Always check the FO2 and MOD appearing on the contents tag, because if
it reflects a limiting ppO2 of more than 1.4 bar you should:
A. Do nothing
1
,B. Set your computer to the higher ppO2
C. Accept it, because now you can go deeper
D. Disregard it and use a more conservative ppO2 of max. 1.4 bar - ANSD.
Disregard it and use a more conservative ppO2 of max. 1.4 bar
Any cylinder containing a gas other than air must be:
A. O2 clean
B. Painted yellow/green
C. Marked with a black X
D. Clearly labeled - ANSD. Clearly labeled
Compared to air, nitrox has a higher concentration of:
A. Oxygen
B. Air
C. Nitrogen
D. Carbon dioxide - ANSA. Oxygen
Diving Nitrox has which potential to provide?
A. shorter decompression limits, shorter repetitive dives
B. longer no-decompression limits, longer repetitive dives
C. longer decompression limits, shorter decompression dives
D. longer no decompression dives, shorter repetitive dives - ANSB. longer
no-decompression limits, longer repetitive dives
Diving with nitrox reduces the exposure to nitrogen, therefore you can`t get
decompression sickness while diving nitrox. Right or Wrong?
A. Wrong
2
, B. Right - ANSA. Wrong
Every nitrox cylinder must be clearly labeled with a contents tag that
includes the following information:
A. Owner of the Total Diving System and MOD
B. FO2 content, MOD, who analyzed, date
C. MOD, date, and number of dives
D. Manufacturer's name and FO2 - ANSB. FO2 content, MOD, who
analyzed, date
How is the ppO2 of a breathing gas calculated?
A. Dividing ambient pressure by the fraction of oxygen (FO2) in the
breathing gas
B. Multiplying cylinder pressure by the fraction of nitrogen (FN2) in the
cylinder
C. Multiplying air pressure by the fraction of oxygen (FO2) in the breathing
gas
D. Multiplying ambient pressure by the fraction of oxygen (FO2) in the
breathing gas - ANSA. Dividing ambient pressure by the fraction of oxygen
(FO2) in the breathing gas
If a diver mistakenly uses a Nitrox cylinder, thinking it was air, he/she would
risk:
A. Nothing, if/he she is not diving deeper than 40 meters
B. Unanticipated CNS oxygen toxicity
C. Decompression sickness
D. Shallow water black out - ANSB. Unanticipated CNS oxygen toxicity
3
Problems. Questions with Correct
Verified Answers. Latest 2026-2027.
Graded A
A common misconception is, that compared to air, Nitrox enables Divers to
dive:
A. deeper
B. longer
C. shorter
D. more shallow - ANSA. deeper
According to the SSI CNS Clock table you have two different CNS Clock
limits. One for a single dive, and one for a 24 hr period. These limits are
for an ppO2 of 1.4 bar:
A. 180 mins single dive / 210 mins 24 hrs
B. 150 mins single dive / 180 mins 24 hrs
C. 120 mins single dive/ 180 mins 24 hrs
D. 180 mins single dive/ 120 mins 24 hrs - ANSB. 150 mins single dive /
180 mins 24 hrs
Always check the FO2 and MOD appearing on the contents tag, because if
it reflects a limiting ppO2 of more than 1.4 bar you should:
A. Do nothing
1
,B. Set your computer to the higher ppO2
C. Accept it, because now you can go deeper
D. Disregard it and use a more conservative ppO2 of max. 1.4 bar - ANSD.
Disregard it and use a more conservative ppO2 of max. 1.4 bar
Any cylinder containing a gas other than air must be:
A. O2 clean
B. Painted yellow/green
C. Marked with a black X
D. Clearly labeled - ANSD. Clearly labeled
Compared to air, nitrox has a higher concentration of:
A. Oxygen
B. Air
C. Nitrogen
D. Carbon dioxide - ANSA. Oxygen
Diving Nitrox has which potential to provide?
A. shorter decompression limits, shorter repetitive dives
B. longer no-decompression limits, longer repetitive dives
C. longer decompression limits, shorter decompression dives
D. longer no decompression dives, shorter repetitive dives - ANSB. longer
no-decompression limits, longer repetitive dives
Diving with nitrox reduces the exposure to nitrogen, therefore you can`t get
decompression sickness while diving nitrox. Right or Wrong?
A. Wrong
2
, B. Right - ANSA. Wrong
Every nitrox cylinder must be clearly labeled with a contents tag that
includes the following information:
A. Owner of the Total Diving System and MOD
B. FO2 content, MOD, who analyzed, date
C. MOD, date, and number of dives
D. Manufacturer's name and FO2 - ANSB. FO2 content, MOD, who
analyzed, date
How is the ppO2 of a breathing gas calculated?
A. Dividing ambient pressure by the fraction of oxygen (FO2) in the
breathing gas
B. Multiplying cylinder pressure by the fraction of nitrogen (FN2) in the
cylinder
C. Multiplying air pressure by the fraction of oxygen (FO2) in the breathing
gas
D. Multiplying ambient pressure by the fraction of oxygen (FO2) in the
breathing gas - ANSA. Dividing ambient pressure by the fraction of oxygen
(FO2) in the breathing gas
If a diver mistakenly uses a Nitrox cylinder, thinking it was air, he/she would
risk:
A. Nothing, if/he she is not diving deeper than 40 meters
B. Unanticipated CNS oxygen toxicity
C. Decompression sickness
D. Shallow water black out - ANSB. Unanticipated CNS oxygen toxicity
3
