FREE IDC Dive Theory & Safety Standards Questions and Answers

Question 1

What is the primary purpose of dive tables?

Accepted Answer

To plan safe dive profiles

Answer

Dive tables are essential tools used by scuba divers to plan and execute dives safely within no-decompression limits. They help divers calculate maximum bottom times and surface intervals based on depth, preventing the accumulation of nitrogen that could lead to decompression sickness.

Question 2

What causes decompression sickness?

Accepted Answer

Rapid ascent causing gas bubbles

Answer

Decompression sickness (DCS), or "the bends," occurs when a diver ascends too quickly, causing dissolved inert gases (primarily nitrogen) in the body to form bubbles in tissues and the bloodstream. These bubbles can lead to a range of symptoms, from joint pain to neurological impairment, as the body fails to off-gas nitrogen safely.

Question 3

What is the recommended ascent rate to prevent decompression sickness?

Accepted Answer

No faster than 30 feet per minute

Answer

A recommended ascent rate of no faster than 30 feet per minute (or 9 meters per minute) is crucial for preventing decompression sickness in scuba diving. This slow ascent allows the body sufficient time to safely off-gas dissolved nitrogen, minimizing the formation of harmful bubbles in the tissues.

Question 4

Why is a safety stop important during a dive?

Accepted Answer

To reduce nitrogen levels safely

Answer

During a dive, nitrogen gas dissolves into a diver's tissues. A safety stop, typically a 3-5 minute stop at 15-20 feet (3-6 meters) near the end of a dive, allows the body to off-gas some of this dissolved nitrogen more slowly. This controlled off-gassing significantly reduces the risk of decompression sickness (DCS), making the ascent safer.

Question 5

What is nitrogen narcosis?

Accepted Answer

Impaired judgment underwater

Answer

Nitrogen narcosis, often called "rapture of the deep," is a reversible alteration in consciousness that occurs while diving at depth. It's caused by the increased partial pressure of nitrogen gas affecting the central nervous system. Symptoms can range from mild euphoria to impaired judgment, disorientation, and reduced motor skills, posing significant safety risks to divers.

IDC - Certified Instructor Development Course Trainer Practice Test

IDC - Certified Instructor Development Course Trainer Practice Test

FREE IDC Dive Theory & Safety Standards Questions and Answers