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Divemaster Final Exam B Actual Exam
2026/2027 – Complete Exam-Style Questions
with Detailed Rationales | 100% Verified |
Pass Guaranteed – A+ Graded
[SECTION 1: Diving Physics & Physiology — Questions 1-20]
Q1. A diver descends to 20 meters (66 feet) on a scuba dive. According to Boyle's Law, if the
diver takes a full breath from a scuba cylinder at this depth and holds it while ascending, what is
the most likely physiological consequence if the ascent is rapid?
A. Air embolism due to lung overexpansion.
B. Nitrogen narcosis due to increased partial pressure.
C. Decompression sickness due to bubble formation.
D. Carbon dioxide retention due to gas density.
Correct Answer: A
Rationale: Boyle's Law states that pressure and volume are inversely proportional. As the diver
ascends, the pressure decreases, causing the air in the lungs to expand. If the glottis is closed
(holding the breath), the expanding air can rupture the lung tissue (barotrauma), leading to
arterial gas embolism (AGE). Nitrogen narcosis (B) is related to depth, not ascent.
Decompression sickness (C) is caused by nitrogen coming out of solution too rapidly, not by
holding breath.
Q2. A diver plans to use a gas mixture of 32% Oxygen and 68% Nitrogen (EANx32). What is the
Maximum Operating Depth (MOD) for this mix if the maximum partial pressure of oxygen
(PO2) is set to 1.4 ATA?
A. 30 meters (100 feet)
B. 34 meters (112 feet)
C. 40 meters (132 feet)
D. 45 meters (148 feet)
,2
Correct Answer: B
Rationale: The MOD is calculated by dividing the maximum allowable PO2 by the fraction of
oxygen in the mix, then subtracting 1 (for surface pressure). MOD (ATA) = (1..32) - 1 =
4.375 - 1 = 3.375 ATA. Converting ATA to meters: 3.375 x 10 = 33.75 meters, commonly
rounded to 34 meters or 112 feet. (A) is too shallow for EANx32, and (C/D) exceed the 1.4 limit.
Q3. According to Henry's Law, which factor primarily increases the amount of nitrogen that
dissolves into the diver's body tissues during a dive?
A. The rate of ascent.
B. The ambient pressure (depth) and duration of the dive.
C. The percentage of oxygen in the breathing gas.
D. The temperature of the water.
Correct Answer: B
Rationale: Henry's Law states that the amount of gas dissolved in a liquid is directly proportional
to the partial pressure of that gas above the liquid. Therefore, deeper depth (higher pressure) and
longer duration increase the amount of nitrogen absorbed. Ascent rate affects how it comes out of
solution, not the initial loading.
Q4. Which physiological effect is a diver most likely to experience if they exceed a CNS oxygen
toxicity limit (Paul Bert effect) while diving?
A. Nausea and vomiting.
B. Convulsions without warning.
C. Painful joints.
D. Itchy skin.
Correct Answer: B
Rationale: The CNS oxygen toxicity mechanism (Paul Bert effect) is characterized by sudden,
convulsions without warning, which can lead to drowning. It is distinct from Pulmonary Oxygen
,3
Toxicity (Lorrain Smith effect) which presents as lung irritation, coughing, or burning in the
chest. Joint pain is associated with Decompression Sickness.
Q5. A diver fills a scuba cylinder to 200 bar at a temperature of 30°C. The cylinder is then stored
in a cool room at 10°C. According to Charles's Law, what will happen to the pressure reading?
A. The pressure will increase.
B. The pressure will decrease.
C. The pressure will remain the same.
D. The volume of gas will decrease.
Correct Answer: B
Rationale: Charles's Law states that at constant volume, pressure is directly proportional to
temperature. As the temperature of the gas drops (cooling), the pressure of the gas inside the
cylinder will decrease. Conversely, heating a tank increases pressure (hot fill).
Q6. Why does a diver often need to add air to their buoyancy compensator device (BCD) as they
descend during a dive?
A. The wetsuit compresses, reducing the diver's displacement.
B. The ambient pressure decreases the volume of air in the BC.
C. The tank becomes negatively buoyant.
D. The diver's lungs become denser.
Correct Answer: A
Rationale: As a diver descends, increased ambient pressure compresses the bubbles in the diver's
wetsuit or drysuit undergarments, reducing their volume and overall displacement (Archimedes'
Principle). This reduces buoyancy (sinking the diver), requiring the addition of air to the BC to
maintain neutral buoyancy. While (B) is true regarding the BC air itself, the dominant factor
requiring continuous addition is suit compression.
, 4
Q7. Which of the following describes the visual effect of looking at objects underwater while
wearing a mask?
A. Objects appear 25% larger and closer.
B. Objects appear 33% larger and closer.
C. Objects appear 33% smaller and further away.
D. Objects appear true to size and distance.
Correct Answer: B
Rationale: Light travels differently through water than through air, and the air space in the mask
refracts light. This causes objects to appear approximately 33% larger and 25% closer than they
actually are. This can affect distance estimation for divers.
Q8. A diver experiences a throbbing headache and euphoria at a depth of 40 meters (130 feet).
This is most likely a sign of:
A. Carbon monoxide poisoning.
B. Nitrogen narcosis.
C. Carbon dioxide retention.
D. High nitrogen partial pressure oxygen toxicity.
Correct Answer: B
Rationale: Nitrogen narcosis (raptures of the deep) is caused by the anesthetic effect of nitrogen
under pressure. It typically starts to become noticeable around 30 meters (100 feet) and presents
as intoxication, euphoria, impaired judgment, or headaches. CO poisoning (A) usually occurs at
the surface or regardless of depth, and CO2 retention (C) causes headache and dyspnea but
usually not euphoria.
Q9. Which condition is caused by the reduction of ambient pressure during ascent, resulting in
nitrogen coming out of solution and forming bubbles in tissues or blood?
A. Barotrauma.
B. Decompression sickness (DCS).
Divemaster Final Exam B Actual Exam
2026/2027 – Complete Exam-Style Questions
with Detailed Rationales | 100% Verified |
Pass Guaranteed – A+ Graded
[SECTION 1: Diving Physics & Physiology — Questions 1-20]
Q1. A diver descends to 20 meters (66 feet) on a scuba dive. According to Boyle's Law, if the
diver takes a full breath from a scuba cylinder at this depth and holds it while ascending, what is
the most likely physiological consequence if the ascent is rapid?
A. Air embolism due to lung overexpansion.
B. Nitrogen narcosis due to increased partial pressure.
C. Decompression sickness due to bubble formation.
D. Carbon dioxide retention due to gas density.
Correct Answer: A
Rationale: Boyle's Law states that pressure and volume are inversely proportional. As the diver
ascends, the pressure decreases, causing the air in the lungs to expand. If the glottis is closed
(holding the breath), the expanding air can rupture the lung tissue (barotrauma), leading to
arterial gas embolism (AGE). Nitrogen narcosis (B) is related to depth, not ascent.
Decompression sickness (C) is caused by nitrogen coming out of solution too rapidly, not by
holding breath.
Q2. A diver plans to use a gas mixture of 32% Oxygen and 68% Nitrogen (EANx32). What is the
Maximum Operating Depth (MOD) for this mix if the maximum partial pressure of oxygen
(PO2) is set to 1.4 ATA?
A. 30 meters (100 feet)
B. 34 meters (112 feet)
C. 40 meters (132 feet)
D. 45 meters (148 feet)
,2
Correct Answer: B
Rationale: The MOD is calculated by dividing the maximum allowable PO2 by the fraction of
oxygen in the mix, then subtracting 1 (for surface pressure). MOD (ATA) = (1..32) - 1 =
4.375 - 1 = 3.375 ATA. Converting ATA to meters: 3.375 x 10 = 33.75 meters, commonly
rounded to 34 meters or 112 feet. (A) is too shallow for EANx32, and (C/D) exceed the 1.4 limit.
Q3. According to Henry's Law, which factor primarily increases the amount of nitrogen that
dissolves into the diver's body tissues during a dive?
A. The rate of ascent.
B. The ambient pressure (depth) and duration of the dive.
C. The percentage of oxygen in the breathing gas.
D. The temperature of the water.
Correct Answer: B
Rationale: Henry's Law states that the amount of gas dissolved in a liquid is directly proportional
to the partial pressure of that gas above the liquid. Therefore, deeper depth (higher pressure) and
longer duration increase the amount of nitrogen absorbed. Ascent rate affects how it comes out of
solution, not the initial loading.
Q4. Which physiological effect is a diver most likely to experience if they exceed a CNS oxygen
toxicity limit (Paul Bert effect) while diving?
A. Nausea and vomiting.
B. Convulsions without warning.
C. Painful joints.
D. Itchy skin.
Correct Answer: B
Rationale: The CNS oxygen toxicity mechanism (Paul Bert effect) is characterized by sudden,
convulsions without warning, which can lead to drowning. It is distinct from Pulmonary Oxygen
,3
Toxicity (Lorrain Smith effect) which presents as lung irritation, coughing, or burning in the
chest. Joint pain is associated with Decompression Sickness.
Q5. A diver fills a scuba cylinder to 200 bar at a temperature of 30°C. The cylinder is then stored
in a cool room at 10°C. According to Charles's Law, what will happen to the pressure reading?
A. The pressure will increase.
B. The pressure will decrease.
C. The pressure will remain the same.
D. The volume of gas will decrease.
Correct Answer: B
Rationale: Charles's Law states that at constant volume, pressure is directly proportional to
temperature. As the temperature of the gas drops (cooling), the pressure of the gas inside the
cylinder will decrease. Conversely, heating a tank increases pressure (hot fill).
Q6. Why does a diver often need to add air to their buoyancy compensator device (BCD) as they
descend during a dive?
A. The wetsuit compresses, reducing the diver's displacement.
B. The ambient pressure decreases the volume of air in the BC.
C. The tank becomes negatively buoyant.
D. The diver's lungs become denser.
Correct Answer: A
Rationale: As a diver descends, increased ambient pressure compresses the bubbles in the diver's
wetsuit or drysuit undergarments, reducing their volume and overall displacement (Archimedes'
Principle). This reduces buoyancy (sinking the diver), requiring the addition of air to the BC to
maintain neutral buoyancy. While (B) is true regarding the BC air itself, the dominant factor
requiring continuous addition is suit compression.
, 4
Q7. Which of the following describes the visual effect of looking at objects underwater while
wearing a mask?
A. Objects appear 25% larger and closer.
B. Objects appear 33% larger and closer.
C. Objects appear 33% smaller and further away.
D. Objects appear true to size and distance.
Correct Answer: B
Rationale: Light travels differently through water than through air, and the air space in the mask
refracts light. This causes objects to appear approximately 33% larger and 25% closer than they
actually are. This can affect distance estimation for divers.
Q8. A diver experiences a throbbing headache and euphoria at a depth of 40 meters (130 feet).
This is most likely a sign of:
A. Carbon monoxide poisoning.
B. Nitrogen narcosis.
C. Carbon dioxide retention.
D. High nitrogen partial pressure oxygen toxicity.
Correct Answer: B
Rationale: Nitrogen narcosis (raptures of the deep) is caused by the anesthetic effect of nitrogen
under pressure. It typically starts to become noticeable around 30 meters (100 feet) and presents
as intoxication, euphoria, impaired judgment, or headaches. CO poisoning (A) usually occurs at
the surface or regardless of depth, and CO2 retention (C) causes headache and dyspnea but
usually not euphoria.
Q9. Which condition is caused by the reduction of ambient pressure during ascent, resulting in
nitrogen coming out of solution and forming bubbles in tissues or blood?
A. Barotrauma.
B. Decompression sickness (DCS).
