half life refers to the characteristic time it takes for
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Nursing Elites

ATI TEAS 7

ATI TEAS 7 science review

1. What does half-life refer to?

Correct answer: D

Rationale: Half-life refers to the time it takes for half of the radioactive atoms in a sample to decay. This means that after one half-life, half of the initial quantity of the radioactive substance will have decayed. Choice A is incorrect because radioactive intensity doesn't completely disappear during half-life. Choice B is incorrect as half-life doesn't refer to the number of neutrons doubling. Choice C is incorrect as half-life doesn't relate to the number of protons changing.

2. During swallowing, what is the role of the epiglottis, a small flap of cartilage located near the base of the tongue?

Correct answer: C

Rationale: The epiglottis plays a crucial role during swallowing by covering the trachea to prevent food or liquid from entering the airway, which could lead to aspiration. By acting as a lid over the trachea, it ensures that food passes down the esophagus to the stomach, preventing it from entering the lungs. Choice A is incorrect as the swallowing reflex is a coordinated muscular action involving the tongue and throat muscles. Choice B is incorrect as grinding food into smaller pieces is primarily the function of the teeth and the initial stages of digestion. Choice D is incorrect as the storage of saliva for lubrication is not a function of the epiglottis, but rather involves salivary glands.

3. Which of the following substances has an acidic pH?

Correct answer: A

Rationale: The correct answer is A, Lemon juice, which has an acidic pH typically around 2 due to its citric acid content. Blood, urine, and salt water are not typically acidic in nature. Blood has a slightly basic pH, urine can vary but is usually slightly acidic to neutral, and salt water is neutral to slightly alkaline. Lemon juice is a commonly known acidic substance, often used in cooking and cleaning due to its acidic properties.

4. Which of the following is NOT one of the major types of bones in the human body?

Correct answer: A

Rationale: The correct answer is A: 'Dense bone'. Dense bone is not a classification of bone types in the human body. The major types of bones include long, short, flat, and irregular bones. Long bones, like the femur, are characterized by being longer than they are wide. Short bones, such as those in the wrist (carpals) and ankle (tarsals), are generally cube-shaped. Flat bones, like the skull or scapula, are thin and provide protection. Irregular bones, such as the vertebrae, have complex shapes that do not fit into the other categories.

5. How do isotopes affect the atomic mass of an element?

Correct answer: B

Rationale: Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. Since the atomic mass of an element is the weighted average of the masses of its isotopes, the presence of isotopes causes the atomic mass of an element to vary slightly. This variation occurs because different isotopes have different masses due to their varying numbers of neutrons. The atomic mass is affected by the abundance of each isotope, leading to a slight fluctuation in the overall atomic mass of the element. Choice A is incorrect because isotopes do influence the atomic mass. Choice C is incorrect because isotopes have different masses, affecting the overall atomic mass. Choice D is incorrect as isotopes typically do not cause a significant variation in atomic mass, but rather a slight fluctuation.

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