PADI OPEN WATER DIVER FINAL EXAM —
350 UNIQUE PRACTICE QUESTIONS WITH
DETAILED RATIONALES
SECTION 1: DIVING PHYSICS (Questions 1–50)
Question 1
According to Boyle's Law, if a diver descends from the surface to 10 meters
(33 feet) of seawater, the volume of a flexible airfilled space will:
A) Double
B) Decrease to onehalf
C) Remain the same
D) Decrease to onequarter
Answer: B
Rationale: Boyle's Law states that at constant temperature, pressure and
volume are inversely proportional. At 10 meters, the absolute pressure is 2
atmospheres (1 atm surface + 1 atm water). Therefore, volume decreases to
half its original size.
,Question 2
The pressure increase from the surface to 20 meters (66 feet) of seawater is:
A) 1 atmosphere
B) 2 atmospheres
C) 3 atmospheres
D) 4 atmospheres
Answer: C
Rationale: Seawater exerts 1 atmosphere of pressure for every 10 meters of
depth. At 20 meters, water pressure = 2 atm. Adding surface pressure (1 atm)
gives total absolute pressure of 3 atmospheres.
Question 3
If an object is neutrally buoyant in fresh water, the same object placed into
salt water would:
A) Sink
B) Either sink or float
C) Do nothing
D) Float
Answer: D
,Rationale: Salt water is denser than fresh water because it contains dissolved
minerals. The object displaces the same volume of water but the salt water
weighs more, creating greater buoyant force.
Question 4
A depth change of 10 meters/33 feet causes a pressure change of:
A) 0.5 bar/ata
B) 1 bar/ata
C) 2 bar/ata
D) 3 bar/ata
Answer: B
Rationale: Every 10 meters (33 feet) of seawater adds 1 bar/atmosphere of
pressure. This is a fundamental principle of diving physics.
Question 5
If you take 6 liters of air from the surface to 20 meters/66 feet, the volume
will be:
A) 6 liters
B) 4 liters
C) 3 liters
D) 2 liters
, Answer: D
Rationale: At 20 meters, absolute pressure is 3 atm (1 atm surface + 2 atm
water). Volume = 6L ÷ 3 = 2L. The air density becomes three times greater
than at the surface.
Question 6
A balloon fully inflated and sealed at 10 meters/33 feet would probably
__________ during ascent to the surface:
A) Shrink
B) Remain the same size
C) Burst
D) Float away
Answer: C
Rationale: As the balloon ascends, surrounding pressure decreases. According
to Boyle's Law, the air inside expands. At 10 meters (2 atm), the air would
double in volume at the surface (1 atm), likely exceeding the balloon's elastic
limit and causing it to burst.
Question 7
What is the relationship between depth in water and pressure?
A) Pressure decreases linearly with depth
350 UNIQUE PRACTICE QUESTIONS WITH
DETAILED RATIONALES
SECTION 1: DIVING PHYSICS (Questions 1–50)
Question 1
According to Boyle's Law, if a diver descends from the surface to 10 meters
(33 feet) of seawater, the volume of a flexible airfilled space will:
A) Double
B) Decrease to onehalf
C) Remain the same
D) Decrease to onequarter
Answer: B
Rationale: Boyle's Law states that at constant temperature, pressure and
volume are inversely proportional. At 10 meters, the absolute pressure is 2
atmospheres (1 atm surface + 1 atm water). Therefore, volume decreases to
half its original size.
,Question 2
The pressure increase from the surface to 20 meters (66 feet) of seawater is:
A) 1 atmosphere
B) 2 atmospheres
C) 3 atmospheres
D) 4 atmospheres
Answer: C
Rationale: Seawater exerts 1 atmosphere of pressure for every 10 meters of
depth. At 20 meters, water pressure = 2 atm. Adding surface pressure (1 atm)
gives total absolute pressure of 3 atmospheres.
Question 3
If an object is neutrally buoyant in fresh water, the same object placed into
salt water would:
A) Sink
B) Either sink or float
C) Do nothing
D) Float
Answer: D
,Rationale: Salt water is denser than fresh water because it contains dissolved
minerals. The object displaces the same volume of water but the salt water
weighs more, creating greater buoyant force.
Question 4
A depth change of 10 meters/33 feet causes a pressure change of:
A) 0.5 bar/ata
B) 1 bar/ata
C) 2 bar/ata
D) 3 bar/ata
Answer: B
Rationale: Every 10 meters (33 feet) of seawater adds 1 bar/atmosphere of
pressure. This is a fundamental principle of diving physics.
Question 5
If you take 6 liters of air from the surface to 20 meters/66 feet, the volume
will be:
A) 6 liters
B) 4 liters
C) 3 liters
D) 2 liters
, Answer: D
Rationale: At 20 meters, absolute pressure is 3 atm (1 atm surface + 2 atm
water). Volume = 6L ÷ 3 = 2L. The air density becomes three times greater
than at the surface.
Question 6
A balloon fully inflated and sealed at 10 meters/33 feet would probably
__________ during ascent to the surface:
A) Shrink
B) Remain the same size
C) Burst
D) Float away
Answer: C
Rationale: As the balloon ascends, surrounding pressure decreases. According
to Boyle's Law, the air inside expands. At 10 meters (2 atm), the air would
double in volume at the surface (1 atm), likely exceeding the balloon's elastic
limit and causing it to burst.
Question 7
What is the relationship between depth in water and pressure?
A) Pressure decreases linearly with depth
