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PADI OPEN WATER FINAL EXAM B
COMPLETE QUESTIONS AND CORRECT
ANSWERS WITH RATIONALES
1. If you take 6 litres of air from the surface to 20 metres / 66 feet, the volume will be:
A) 6 litres
B) 4 litres
C) 3 litres
D) 2 litres
*Rationale: At 20 metres (66 feet), the pressure is 3 ATA (1 ATA at surface + 2 ATA for 20 m of
depth). Applying Boyle’s Law (P₁×V₁ =
P₂×V₂), 1 ATA × 6 L = 3 ATA × V₂ → V₂ = 2 litres.*
2. A balloon fully inflated and sealed at 10 metres/33 feet is taken to the surface. The
balloon will probably:
A) Shrink to half its size and the air density will increase by a factor of 2
B) Expand to twice its size and the air density will decrease by half
C) Shrink to half its size and the air density will decrease by half D) Expand to twice its size
and the air density will increase by a factor of 2
Rationale: At 10 metres (33 feet), pressure is 2 ATA. At the surface, pressure is 1 ATA. According
to Boyle’s Law, volume doubles as pressure halves, and density decreases by half (density is
inversely related to volume). The balloon will expand to twice its original size and the air inside
will be less dense.
3. If an object is neutrally buoyant (does not sink or float) in fresh water, the same object
placed into salt water would:
A) Sink
B) Either sink or float
C) Do nothing
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D) Float
Rationale: Salt water is denser than fresh water because it contains dissolved minerals. This
greater density causes more upward force (buoyancy) on an object. Therefore, an object neutrally
buoyant in fresh water will float in salt water.
4. As a newly certified PADI Open Water Diver, you are trained to dive with a buddy to a
maximum depth of:
A) 12 metres / 40 feet
B) 18 metres / 60 feet
C) 30 metres / 100 feet D) 40 metres / 130 feet
Rationale: The PADI Open Water Diver certification limits divers to a maximum depth of 18
metres (60 feet). This depth limit reduces risks related to nitrogen narcosis and decompression
sickness. Deeper dives require advanced training.
5. As you descend in water, the surrounding pressure:
A) Decreases
B) Stays the same
C) Increases
D) Fluctuates randomly
Rationale: Water pressure increases with depth due to the weight of the water above. Every 10
metres (33 feet) of seawater adds approximately 1 bar (ATA) of pressure. At the surface, pressure
is 1 ATA; at 10 metres, it becomes 2 ATA.
6. A depth change of 10 metres / 33 feet causes a pressure change of:
A) 0.5 bar / ATA
B) 1 bar / ATA
C) 2 bar / ATA D) 3 bar / ATA
*Rationale: For every 10 metres (33 feet) of depth change, pressure changes by exactly 1 bar /
ATA. This is a fundamental rule derived from the weight of a column of water. *
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PADI OPEN WATER FINAL EXAM B
COMPLETE QUESTIONS AND CORRECT
ANSWERS WITH RATIONALES
1. If you take 6 litres of air from the surface to 20 metres / 66 feet, the volume will be:
A) 6 litres
B) 4 litres
C) 3 litres
D) 2 litres
*Rationale: At 20 metres (66 feet), the pressure is 3 ATA (1 ATA at surface + 2 ATA for 20 m of
depth). Applying Boyle’s Law (P₁×V₁ =
P₂×V₂), 1 ATA × 6 L = 3 ATA × V₂ → V₂ = 2 litres.*
2. A balloon fully inflated and sealed at 10 metres/33 feet is taken to the surface. The
balloon will probably:
A) Shrink to half its size and the air density will increase by a factor of 2
B) Expand to twice its size and the air density will decrease by half
C) Shrink to half its size and the air density will decrease by half D) Expand to twice its size
and the air density will increase by a factor of 2
Rationale: At 10 metres (33 feet), pressure is 2 ATA. At the surface, pressure is 1 ATA. According
to Boyle’s Law, volume doubles as pressure halves, and density decreases by half (density is
inversely related to volume). The balloon will expand to twice its original size and the air inside
will be less dense.
3. If an object is neutrally buoyant (does not sink or float) in fresh water, the same object
placed into salt water would:
A) Sink
B) Either sink or float
C) Do nothing
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D) Float
Rationale: Salt water is denser than fresh water because it contains dissolved minerals. This
greater density causes more upward force (buoyancy) on an object. Therefore, an object neutrally
buoyant in fresh water will float in salt water.
4. As a newly certified PADI Open Water Diver, you are trained to dive with a buddy to a
maximum depth of:
A) 12 metres / 40 feet
B) 18 metres / 60 feet
C) 30 metres / 100 feet D) 40 metres / 130 feet
Rationale: The PADI Open Water Diver certification limits divers to a maximum depth of 18
metres (60 feet). This depth limit reduces risks related to nitrogen narcosis and decompression
sickness. Deeper dives require advanced training.
5. As you descend in water, the surrounding pressure:
A) Decreases
B) Stays the same
C) Increases
D) Fluctuates randomly
Rationale: Water pressure increases with depth due to the weight of the water above. Every 10
metres (33 feet) of seawater adds approximately 1 bar (ATA) of pressure. At the surface, pressure
is 1 ATA; at 10 metres, it becomes 2 ATA.
6. A depth change of 10 metres / 33 feet causes a pressure change of:
A) 0.5 bar / ATA
B) 1 bar / ATA
C) 2 bar / ATA D) 3 bar / ATA
*Rationale: For every 10 metres (33 feet) of depth change, pressure changes by exactly 1 bar /
ATA. This is a fundamental rule derived from the weight of a column of water. *
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