PADI Open Water Final Exam B
ACTUAL EXAM 2026/2027 | PADI
Open Water B | Verified Q&A | Pass
Guaranteed - A+ Graded
Section 1 – Diving Physics (Pressure, Buoyancy, Gas Laws) (Questions 1–10)
Q1: According to Boyle's Law, if a diver descends from the surface (1 ata) to 20 meters (66 feet, 3 ata),
what happens to the volume of an air-filled flexible air space?
A. Volume doubles
B. Volume stays the same
C. Volume reduces to one-half
D. Volume reduces to one-third [CORRECT]
Correct Answer: D
Rationale: Boyle's Law states volume is inversely proportional to pressure. At 20 meters/66 feet,
absolute pressure is 3 ata, so volume compresses to 1/3 of surface volume.
Q2: A diver is neutrally buoyant at 15 meters (49 feet) while wearing an aluminum 80 cylinder with 200
bar/3000 psi. As the diver breathes the tank down to 50 bar/750 psi, what buoyancy change occurs?
A. The diver becomes more negatively buoyant
B. The diver becomes more positively buoyant [CORRECT]
C. No change in buoyancy
D. The diver becomes negatively buoyant then neutral
Correct Answer: B
Rationale: As air is consumed from the cylinder, the tank weighs less (air has weight). The diver
becomes more positively buoyant and needs to add air to the BCD to maintain neutral buoyancy.
Q3: Using the PADI RDP/eRDP, a diver completes a dive to 18 meters (60 feet) for 25 minutes. What is
the pressure group at the surface?
A. Pressure Group H
B. Pressure Group J
C. Pressure Group L
D. Pressure Group N [CORRECT]
Correct Answer: D
, Rationale: On the PADI RDP Table 1, locate 18 meters (60 feet), move across to 25 minutes, which falls
between the 23 and 27-minute lines, giving Pressure Group N.
Q4: A diver descends to 30 meters (100 feet). What is the absolute pressure in atmospheres absolute
(ata)?
A. 2 ata
B. 3 ata
C. 4 ata [CORRECT]
D. 5 ata
Correct Answer: C
Rationale: Absolute pressure at depth is calculated as (depth in meters ÷ 10) + 1; at 30 meters, this
equals 3 + 1 = 4 ata, representing one atmosphere of surface pressure plus three atmospheres of water
pressure.
Q5: According to Archimedes' Principle, a diver will float when:
A. The diver's weight is greater than the weight of displaced water
B. The diver's weight is less than the weight of displaced water [CORRECT]
C. The diver's weight equals the weight of displaced water
D. The diver's density is greater than water
Correct Answer: B
Rationale: Archimedes' Principle states that an object floats when the weight of displaced water
exceeds the object's weight; positive buoyancy occurs when buoyant force exceeds gravitational force.
Q6: A diver's mask contains 200 mL of air at the surface. At 20 meters (66 feet), what is the new mask
volume if the diver does not equalize?
A. 100 mL
B. 67 mL [CORRECT]
C. 50 mL
D. 33 mL
Correct Answer: B
Rationale: At 20 meters (3 ata), Boyle's Law reduces volume to 1/3 of surface volume; 200 mL ÷ 3 = 67
mL, creating a vacuum that causes mask squeeze if not equalized by adding air.
Q7: According to Dalton's Law, what happens to the partial pressure of oxygen as a diver descends
deeper?
A. It decreases proportionally with depth
B. It increases proportionally with absolute pressure [CORRECT]
C. It remains constant regardless of depth
D. It decreases due to nitrogen absorption
Correct Answer: B
Rationale: Dalton's Law states that partial pressure equals total pressure multiplied by gas fraction; as
absolute pressure increases with depth, the partial pressure of each component gas (including oxygen)
increases proportionally.
ACTUAL EXAM 2026/2027 | PADI
Open Water B | Verified Q&A | Pass
Guaranteed - A+ Graded
Section 1 – Diving Physics (Pressure, Buoyancy, Gas Laws) (Questions 1–10)
Q1: According to Boyle's Law, if a diver descends from the surface (1 ata) to 20 meters (66 feet, 3 ata),
what happens to the volume of an air-filled flexible air space?
A. Volume doubles
B. Volume stays the same
C. Volume reduces to one-half
D. Volume reduces to one-third [CORRECT]
Correct Answer: D
Rationale: Boyle's Law states volume is inversely proportional to pressure. At 20 meters/66 feet,
absolute pressure is 3 ata, so volume compresses to 1/3 of surface volume.
Q2: A diver is neutrally buoyant at 15 meters (49 feet) while wearing an aluminum 80 cylinder with 200
bar/3000 psi. As the diver breathes the tank down to 50 bar/750 psi, what buoyancy change occurs?
A. The diver becomes more negatively buoyant
B. The diver becomes more positively buoyant [CORRECT]
C. No change in buoyancy
D. The diver becomes negatively buoyant then neutral
Correct Answer: B
Rationale: As air is consumed from the cylinder, the tank weighs less (air has weight). The diver
becomes more positively buoyant and needs to add air to the BCD to maintain neutral buoyancy.
Q3: Using the PADI RDP/eRDP, a diver completes a dive to 18 meters (60 feet) for 25 minutes. What is
the pressure group at the surface?
A. Pressure Group H
B. Pressure Group J
C. Pressure Group L
D. Pressure Group N [CORRECT]
Correct Answer: D
, Rationale: On the PADI RDP Table 1, locate 18 meters (60 feet), move across to 25 minutes, which falls
between the 23 and 27-minute lines, giving Pressure Group N.
Q4: A diver descends to 30 meters (100 feet). What is the absolute pressure in atmospheres absolute
(ata)?
A. 2 ata
B. 3 ata
C. 4 ata [CORRECT]
D. 5 ata
Correct Answer: C
Rationale: Absolute pressure at depth is calculated as (depth in meters ÷ 10) + 1; at 30 meters, this
equals 3 + 1 = 4 ata, representing one atmosphere of surface pressure plus three atmospheres of water
pressure.
Q5: According to Archimedes' Principle, a diver will float when:
A. The diver's weight is greater than the weight of displaced water
B. The diver's weight is less than the weight of displaced water [CORRECT]
C. The diver's weight equals the weight of displaced water
D. The diver's density is greater than water
Correct Answer: B
Rationale: Archimedes' Principle states that an object floats when the weight of displaced water
exceeds the object's weight; positive buoyancy occurs when buoyant force exceeds gravitational force.
Q6: A diver's mask contains 200 mL of air at the surface. At 20 meters (66 feet), what is the new mask
volume if the diver does not equalize?
A. 100 mL
B. 67 mL [CORRECT]
C. 50 mL
D. 33 mL
Correct Answer: B
Rationale: At 20 meters (3 ata), Boyle's Law reduces volume to 1/3 of surface volume; 200 mL ÷ 3 = 67
mL, creating a vacuum that causes mask squeeze if not equalized by adding air.
Q7: According to Dalton's Law, what happens to the partial pressure of oxygen as a diver descends
deeper?
A. It decreases proportionally with depth
B. It increases proportionally with absolute pressure [CORRECT]
C. It remains constant regardless of depth
D. It decreases due to nitrogen absorption
Correct Answer: B
Rationale: Dalton's Law states that partial pressure equals total pressure multiplied by gas fraction; as
absolute pressure increases with depth, the partial pressure of each component gas (including oxygen)
increases proportionally.
