1.
What should you do to prevent mask squeeze (a sucking or pulling feeling on your face and eyes)?
Correct Answer
D. Blow into your mask through your nose
Explanation
Blowing into your mask through your nose can help to equalize the pressure inside and outside the mask, preventing mask squeeze. This technique helps to balance the pressure and alleviate the sucking or pulling feeling on your face and eyes.
2.
The most important feature for consideration when selecting a regulator is.
Correct Answer
C. Ease of Breathing
Explanation
When selecting a regulator, the most important feature to consider is ease of breathing. This is crucial because a regulator is responsible for supplying air to the diver underwater. If the regulator is not easy to breathe from, it can cause discomfort, fatigue, and potentially compromise the diver's safety. Therefore, prioritizing ease of breathing ensures a comfortable and efficient diving experience.
3.
Sound travels well in water and it is difficult to tell.
Correct Answer
A. Where the sound is coming from
Explanation
Sound travels faster in water than in air, making it hard to determine its source.
4.
The best place to carry an alternative air source is:
Correct Answer
D. Attached to the triangle area between your chin and your chest
Explanation
The best place to carry an alternative air source is attached to the triangle area between your chin and your chest. This location ensures that the air source is easily accessible in case of an emergency. It allows for quick and efficient retrieval, minimizing the time it takes to access the alternative air source.
5.
How can you avoid vertigo (dizziness and confusion) on a dive?
Correct Answer
C. Ascent (go up) and descend (go down) along the bottom or a reference line
Explanation
Focusing on a fixed reference will prevent the effects of vertigo.
6.
Underwater visibility (how far you can see horizontally) can be affected by.
Correct Answer
D. All of the above
Explanation
Underwater visibility can be affected by various factors such as water movement, weather conditions, and suspended particles in the water. Water movement, such as currents or waves, can stir up sediment and decrease visibility. Weather conditions, such as rain or wind, can also impact visibility by introducing more particles into the water or causing surface turbulence. Additionally, suspended particles, like floating silt or algae, can reduce visibility by scattering or absorbing light. Therefore, all of these factors can contribute to the decrease in underwater visibility.
7.
Most diver injuries caused by aquatic animals happen because:
Correct Answer
C. The animal is protecting itself from you
Explanation
The correct answer is that the animal is protecting itself from you. When divers encounter aquatic animals, they may feel threatened or perceive the diver as a potential predator. In order to defend themselves, these animals may exhibit aggressive behavior, such as biting or stinging. It is important for divers to respect the animals' space and behavior, and to avoid any actions that may provoke defensive reactions.
8.
Decompression sickness (DCS) is a condition that can be life-threatening. What forms in the bloodstream and tissues can cause this condition.
Correct Answer
A. Nitrogen bubbles
Explanation
Decompression sickness occurs when nitrogen bubbles form in the bloodstream and tissues. During activities such as scuba diving or flying at high altitudes, the body absorbs nitrogen from the air. If the pressure changes too quickly, such as during a rapid ascent or descent, the nitrogen can form bubbles in the body. These bubbles can block blood vessels, leading to various symptoms like joint pain, fatigue, and even paralysis. Therefore, the presence of nitrogen bubbles in the bloodstream and tissues can cause decompression sickness, making it a life-threatening condition.
9.
The air in a scuba tank is comprised of _____ oxygen and _____ nitrogen.
Correct Answer
B. 21%, 79%
Explanation
The air in a scuba tank is typically comprised of 21% oxygen and 79% nitrogen. This is similar to the composition of atmospheric air. However, it’s worth noting that there are other gas mixtures used in scuba diving depending on the specific requirements of the dive.
10.
An object is neutrally buoyant when it displaces an amount of water ________ its own weight.
Correct Answer
C. Equal to
Explanation
An object is neutrally buoyant when it displaces an amount of water equal to its own weight. This means that the upward buoyant force acting on the object is equal to the downward force of gravity, resulting in a net force of zero. As a result, the object neither sinks nor floats, but remains suspended in the water at a specific depth.
11.
The most important feature of any weight system is.
Correct Answer
D. A quick release mechanism
Explanation
A quick release mechanism is the most important feature of any weight system because it allows for easy and efficient adjustments. This is essential for diver safety and convenience. It allows divers to easily shed their weights in case of an emergency or when needing to surface quickly. While other factors like the size, shape, and ease of adjustment of weights are important, the quick release mechanism is crucial for immediate safety and adaptability during a dive, making it an essential feature of a weight system in scuba diving.