IDC Guide

Dive Theory Mock Exam E

Dive Theory Mock Exam E

Dive Theory Mock Exam E

If you find this useful to your IDC Revision / Studies, you will be glad to hear that you can buy the full Exam Pack that includes 10 Standards and Dive Theory Mock PADI exams plus a bonus 75 question Pre-IDC Exam paper with answer keys.

Please click the link and BUY all 3 complete IDC revision packs that includes lots of revision documents and 11 practice mock exams, the exams include all the questions and answers you will need to revise to PASS the PADI IDC

PADI Instructor Development Dive Theory Exam

Constants used for Dive Theory Exams


  • 1 litre of salt water weighs 1.03 kilograms
  • 1 litre of fresh water weighs 1 kilogram
  • Pressure increases by 1 ATM every 10 metres of salt water
  • Pressure increases by 1 ATM every 10.3 metres of fresh water
  • Pressure changes per unit of salt water = 0.100 ATM/m
  • Pressure changes per unit of fresh water = 0.097 ATM/m


1) Approximately how much denser is the air a diver
breathes at 30 metres as compared to the surface?
a) equivalent to the surface density
b) two times as dense
c) three times as dense
d) four times as dense

2) As depth increases underwater colours disappear. The
first colour to disappear is ________ and this is due to
the water’s ability to ___________ light.
a) red/absorb
b) blue/diffuse
c) red/refract
d) white/bend

3) A scuba tank containing 1.5% of carbon monoxide at
the surface is taken down to 30m. If a diver were to
breathe from the tank at this depth, it would have the
same effect as breathing _____________ percent of
carbon monoxide at the surface
a) 1.5 %
b) 3 %
c) 6 %
d) 4 %

4) Because water is so much _____________ than air,
sound travels __________ times faster in water than
in air.
a) warmer/four
b) denser/four
c) denser/twenty
d) colder/twenty

5) If an object that weighs 95 kilograms is neutrally
buoyant in salt water, what is the volume of water the
object displaces?
a) 95 litres.
b) 92.2 litres.
c) 97.8 litres.
d) The answer can not be determined.

6) In the object described in question 5 was placed in
fresh water it would:
a) sink.
b) float.
c) remain neutral.
d) the answer can not be determined from the
the information given.

7) The absolute pressure in 32 metres of salt water is:
a) 3.2 ATA
b) 4.0 ATA
c) 4.2 ATA
d) 5.2 ATA

8) Approximately how much air must be pumped down
from the surface to fill a 40 litre container if it lies in
20 metres of salt water?
a) 40 litres
b) 80 litres.
c) 116.5 litres.
d) 120 litres

9) Because the heat capacity of water is thousands of
times ___________ than air, water conducts heat more
than ¬¬¬¬¬________ times better than air.
a) greater/20
b) greater/4
c) less/20
d) less/4

10) If an air-filled balloon is taken to a depth of 20 metres
what is the approximate partial pressure of oxygen in
the balloon?
a) 0.2 ATA
b) 0.6 ATA
c) 0.8 ATA
d) 2.4 ATA

11) A 250 kilogram anchor that displaces 65 litres of water
lies on the bottom in 30m of salt water. What is the
minimum amount of water needs to be displaced from
a lifting device to the anchor to the surface?
a) 177.7 litres
b) 200 litres
c) 740 litres
d) 315 litres

12) If it takes a diver 80 minutes to breathe all the air from
a scuba tank at the surface, approximately how long
will the air in that tank last at 30 metres?
a) 80 minutes
b) 60 minutes
c) 26 minutes
d) 20 minutes


1) Factors that influence a diver’s susceptibility to
decompression sickness include:
a) smoking before/after a dive.
b) consuming alcohol before/after a dive.
c) obesity.
d) all of the above.

2) After a dive, _________________may be present
in a diver’s circulation system, even though they
do not display any symptoms of decompression
a) transparent bubbles
b) silent bubbles
c) vascular bubbles
d) micro bubbles

3) What part of the ear is most affected by pressure
a) middle ear
b) inner ear
c) outer ear
d) ear lobe

4) What part of the body is a diver likely to damage
if they try to force equalization?
a) a round window rupture
b) an eardrum rupture
c) an oval window rupture
d) a reverse squeeze

5) Cigarette smoking _____________ the body’s ability
to transport oxygen due to an increased _________
level in the lungs. This is why cigarette smoking
should be avoided prior to dive.
a) decreases/nicotine
b) increases/ nitrogen
c) increases/carbon dioxide
d) decreases/carbon monoxide

6) An excessively tight neck seal or hood, may cause
unconsciousness due to __________________. This
is called __________________.
a) reduced blood supply to the brain/carotid-
sinus reflex
b) carbon monoxide poisoning/shallow water
c) low carbon dioxide levels/hypocapnia
d) low oxygen levels/hypoxemia

7) A pressure related injury is called a barotrauma. This
type of injury can occur while diving ___________.
a) during descent or ascent
b) only at depth
c) during descent only
d) below 30 metres

8) If a diver complains of numbness in his extremities
several hours after a dive, he may be suffering from:
a) gas narcosis
b) contaminated air poisoning
c) decompression illness
d) both a and c are correct

9) The most serious of lung injuries is called:
a) mediastinal emphysema
b) pneumothorax
c) subcutaneous emphysema
d) air embolism

10) If a diver ruptures an ear drum while diving in cold
water, they may experience ______________ as the
water comes into contact with the vestibular canals.
a) vertigo
b) a squeeze
c) euphoria
d) tunnel vision

11) _________________ is a substance contained within
the red blood cells which aids the transport of oxygen
throughout the human body system.
a) cholesterol
b) gammaglobulin
c) plasma
d) hemoglobin

12) The symptoms of a lung-expansion injury tend to
appear ___________ whereas the symptoms of
decompression sickness usually __________________.
a) slowly over an extended time/ occur immediately
upon surfacing
b) within the first 24 hours/ appear within minutes
after the dive.
c) immediately after the dive/ are slower to occur
d) only after surfacing/ usually appear at depth

Recreational Dive Planner

1) Divers must follow special procedures to use the
PADI RDP at altitudes higher than ____________.
a) 300 metres or 1000 feet
b) 500 metres or 1500 feet
c) 2400 metres or 8000 feet
d) 3000 metres or 10,000 feet

2) The RDP has shorter surface interval times and
allows longer repetitive dive times than previous
dive tables because:
a) recreational divers have a limited air supply
b) it was tested in a recompression chamber
c) it was designed with a faster gas washout
tissue compartment
d) it was designed for decompression diving

3) A ______ tissue compartment model was used to
determine the no decompression limits for
RDP and the surface interval credit table was
calculated using a tissue half-time of _________
a) 12 / 120
b) 12/ 120
c) 14 / 120
d) 14 / 60

4) If a holiday diver makes three dives every day for 5
days, what is the recommended minimum time the
diver should wait before flying in a commercial
aircraft according to the flying after diving rules?
a) 4 hours
b) 18 hours
c) 24 hours
d) 12 hours

Use the eRDPml to answer the following:

5) What is a diver’s pressure group after surfacing from
A dive to 9 metres for 79 minutes?
a) M
b) N
c) O
d) P

6) If a diver exists the water in pressure group R, what
would their new pressure group be after a 55
minute surface interval?
a) E
b) F
c) G
d) H

Use the eRDPml to answer the following:
7) What is the diver’s pressure group after a dive to
20 metres for 42 minutes?
a) S
b) T
c) M
d) Q

8) You dive to 17 metres for 26 minutes. After a 30
minute surface interval, what is your pressure group?
a) F
b) D
c) G
d) E

9) What is the minimum surface interval required between
a dive to 20 metres for 44 minutes followed by a dive
to 14 metres for 38 minutes.
a) 11 minutes
b) 12 minutes
c) 14 minutes
d) 18 minutes

10) What is the minimum surface interval required to make
the following dive? Pressure group after previous
dive: S. Second dive: 15 metres for 55 min.
a) 1:28
b) 1:30
c) 2:28
d) 1:10

11) You plan to make three dives. The first will be to 23m
for 30 minutes, followed by a one hour, 30 minute
surface interval. The second dive will be to 22 m for
18 minutes. If this is followed by a one hour, 20 minute
surface interval, what is the no decompression limit for
a repetitive dive to 8 m?
a) 191 minutes
b) 193 minutes
c) 194 minutes
d) 200 minutes

12) A diver plans to do a multilevel dive with three levels.
30,20 and 12 metres. They plan to stay the multilevel
limit at each depth – approx. how long will they spend
underwater? (you may ignore ascent time, but not
required safety stop time.)
a) 81 minutes
b) 80 minutes
c) 83 minutes
d) 90 minutes

General Skills & The Environment

1) Tides are most affected by ____________.
a) seismic activity and wind speed
b) major ocean currents
c) fresh water meeting salt water
d) the relative position of the sun, moon and

2) Near drowning victims should always see a doctor
even if they feel fine because:
a) they may have aspirated water that can cause
damage to the lungs & secondary drowning
b) they may develop decompression illness
c) they are probably hypothermic
d) none of the above

3) A diver makes a slashing motion across their throat,
they are signalling that:
a) they wants to remain at this depth
b) they have seen a dead creature underwater
c) they are low on air
d) they are out of air

4) Aquatic life injury signs and symptoms may include:
a) local swelling and inflammation
b) cherry red lips and fingernail beds
c) a false sense of wellbeing or euphoria
d) both a and c are correct

5) When deciding which search pattern to use to find a
Lost object you should consider:
a) bottom topography and equipment available
b) size of the object and size of the search area
c) water conditions and visibility
d) all of the above

6) The environmental element that is primarily
responsible for causing waves is:
a) upwelling
b) wind
c) the gravitational pull from the sun and from
the moon
d) bottom topography

7) When lifting an object to the surface your first step
Is to:
a) Secure the lift bag to it
b) Test the rigging
c) mark it with a buoy
d) Choose a lift bag with the capacity close to the
objects weight

8) What is the primary concern when dealing with an
unconscious diver in the water?
a) get the diver to a place where first aid,
ventilations and CPR may be effectively administered
b) remove the diver’s equipment
c) administer CPR
d) locate the dive buddy to find out what happened

9) The major currents that flow in the North Pacific and
North Atlantic oceans move in a __________ direction.
a) southerly
b) clockwise
c) counter clockwise
d) northerly

10) When one rescuer is administering CPR maintain a
cycle of ___________ chest compressions, followed by
________ ventilations.
a) 5:1
b) 15:1
c) 80:4
d) 30:2

11) The ideal way a diver checks for the proper amount of
weight required for a dive is to:
a) perform a buoyancy check at the surface before
the dive. Deflate the BCD while holding a normal
breath so that the diver floats at eye level.
b) calculate it using 10% of your body weight for
fresh water and 15% for salt water
c) check their log book and use the same amount
of weight used on the previous dive.
d) perform a buoyancy check in a pool then add
several extra Kilograms to compensate for salt

12) If you are standing on a boat facing the bow, the side
to your right is:
a) bow
b) aft
c) port
d) starboard


1) A malfunction in a _____________ regulator should
result in a continuous air flow.
a) free flow
b) open circuit
c) balanced
d) fail safe

2) Divers should avoid diving to the no decompression
limits because ___________ may not be precise –
even a slight variation can put divers at risk if limits
are pushed
a) diving computers
b) timing devises
c) depth gauges
d) all of the above are correct

3) If a scuba tank has fallen from a moving vehicle,
it is recommended that it is _______________
before filling and use.
a) visually inspected
b) hydrostatic/pressure tested
c) repainted
d) emptied and refilled with fresh air

4) When diving in extremely cold water, a regulator
that has a(n) ______________ may be protected
from freezing up.
a) downstream valve
b) environmentally sealed first stage
c) fail safe design
d) closed circuit design

5) Downstream or pilot valves are most likely found in
the ____________ of scuba regulators.
a) second stage
b) first stage
c) first and second stages
d) high pressure ports

6) A burst-disk is intended to protect against:
a) inhaling water when breathing from a snorkel.
b) rupturing a BCD if it is overinflated.
c) damage to a scuba tank that may occur from
over pressurisation.
d) none of the above

7) A _________ connection on a scuba tank allows the
regulator to be screwed directly into the tank valve.
a) DIN
b) yoke screw or A clamp
c) K valve
d) dual tank manifold

8) When used as designed a J valve will:
a) act as a warning device, alerting of low tank pressure
b) allow the diver to monitor air pressure without using
an SPG
c) give the diver extra air if he wants it.
d) both a and c are correct

9) The scuba regulator’s first stage is designed to:
a) reduce high tank pressure to intermediate
b) transport high pressure gas from the tank to
the second stage
c) reduce intermediate pressure gas to ambient
Pressure for the diver to breathe
d) reduce high pressure gas from the tank
to ambient pressure

10) A ________ depth gauge will give theoretical depths
rather than actual depth when diving at altitudes
above 300 metres.
a) closed bourdon tube
b) open bourdon tube
c) oil filled
d) capillary

11) Scuba regulators are referred to as ________________
because they are activated by the diver inhalation and
exhaust is vented into the water.
a) closed circuit, upstream valves
b) open circuit, demand valves
c) ambient pressure, balanced valves
d) demand, free flowing valves

12) What substance may form and corrode a steel tank
if water gets inside?
a) aluminium oxide
b) iron oxide (rust)
c) hydrogen peroxide
d) salt crystal

If you find this useful to your IDC Revision / Studies, you will be glad to hear that you can buy the full Exam Pack that includes 10 Standards and Dive Theory Mock PADI exams plus a bonus 75 question Pre-IDC Exam paper with answer keys.

Please click the link and BUY all 3 complete IDC revision packs that includes lots of revision documents and 11 practice mock exams, the exams include all the questions and answers you will need to revise to PASS the PADI IDC

Scroll to Top