HESI A2
Chemistry Hesi A2
1. Which is a triatomic allotrope of oxygen?
- A. Ozone
- B. Water
- C. Acidic oxide
- D. Carbon dioxide
Correct answer: A
Rationale: Ozone (O3) is a triatomic allotrope of oxygen. It differs from the common diatomic oxygen molecule (O2) by having three oxygen atoms bonded together. Ozone is known for its protective role in the Earth's atmosphere, absorbing most of the Sun's harmful ultraviolet radiation. Water (H2O) is a compound composed of two hydrogen atoms and one oxygen atom. Acidic oxide and carbon dioxide are not triatomic allotropes of oxygen. Carbon dioxide consists of one carbon atom and two oxygen atoms, while acidic oxides refer to compounds where oxygen is bonded with other elements to form oxides, and they are not allotropes of oxygen.
2. Select the meaning of the word 'tenuous' in the sentence: 'Patients in this wing often have a tenuous hold on reality.'
- A. Judicious
- B. Deleted
- C. Frantic
- D. Fragile
Correct answer: D
Rationale: In this context, the word 'tenuous' is used to describe a weak or delicate hold on reality. 'Fragile' is the correct choice as it conveys the idea of something being easily broken or damaged, which aligns with the meaning of 'tenuous' in the sentence. Choice A, 'Judicious,' means having good judgment, which is unrelated to the context. Choice B, 'Deleted,' means removed or erased, which is not synonymous with 'tenuous.' Choice C, 'Frantic,' means panicked or desperate, which does not capture the delicate or weak nature implied by 'tenuous.'
3. Multiply: 5.04 × 2 =
- A. 1.008
- B. 10.08
- C. 10.8
- D. 18
Correct answer: B
Rationale: To multiply 5.04 by 2, you simply multiply the two numbers together: 5.04 x 2 = 10.08. Therefore, the correct answer is B. Choice A (1.008) is incorrect as it represents the result of dividing 5.04 by 5 instead of multiplying. Choice C (10.8) is incorrect as it is the result of rounding 10.08 to the nearest whole number. Choice D (18) is incorrect as it results from adding 5.04 and 2 instead of multiplying.
4. Which of the following is a conclusion that a reader can draw from this passage?
- A. Humans are not the only mammals that exhibit symptoms when infected by Borrelia burgdorferi.
- B. The life cycle of an uninfected tick includes a dormant phase before the nymph stage, which is not excluded.
- C. Unless a tick feeds on an infected mouse or squirrel, it will not spread Lyme disease.
- D. The combination of fever, headache, and joint pain is not a definite indication of Lyme disease.
Correct answer: C
Rationale: The correct answer is C. The passage clearly states that for Lyme disease to spread, a tick must feed on an infected host, such as a mouse or squirrel. This conclusion can be drawn from the information provided in the extract. Choice A is incorrect because the passage does not specify that humans are the only mammals that exhibit symptoms when infected by Borrelia burgdorferi. Choice B is incorrect as the passage mentions that the life cycle of an uninfected tick includes a dormant phase before the nymph stage, without excluding it. Choice D is incorrect because the passage does not state that the combination of fever, headache, and joint pain is a definitive sign of Lyme disease.
5. Simplify the expression: -5 + (-8)
- A. -13
- B. 8
- C. 13
- D. -5
Correct answer: A
Rationale: When adding two negative numbers, you add their absolute values and keep the negative sign. In this case, -5 + (-8) is equal to -13 because the absolute values of 5 and 8 add up to 13, and the negative sign is retained. Choice B (8) is incorrect because adding two negative numbers results in a negative sum. Choice C (13) is incorrect as it doesn't consider the negative signs of the numbers being added. Choice D (-5) is incorrect because it does not account for the addition of the two negative numbers.
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