HESI A2
HESI A2 Chemistry Questions
1. What is 119 K in degrees Celsius?
- A. 32°C
- B. -154°C
- C. 154°C
- D. 0°C
Correct answer: B
Rationale: To convert Kelvin (K) to Celsius (°C), you subtract 273.15 from the Kelvin value. Therefore, 119 K - 273.15 = -154.15°C. The negative sign indicates that the temperature is below freezing. When rounded to the nearest whole number, -154.15°C is approximately -154°C. Choice A and Choice C are incorrect as they do not reflect the correct conversion from Kelvin to Celsius. Choice D is incorrect as it corresponds to the freezing point of water in Celsius, not the conversion of 119 K.
2. What is the main idea of the passage?
- A. Senior citizens need to increase their calcium and vitamin D intake.
- B. The food pyramid was revised to reflect the needs of seniors.
- C. Physical activity is a new addition to the food pyramid.
- D. The revised food pyramid looks more like a food square.
Correct answer: B
Rationale: The passage discusses the revision of the food pyramid specifically to address the unique dietary needs of seniors. It emphasizes how the changes were made based on ongoing research and analysis, indicating a broader focus on senior nutrition rather than just individual nutrients or exercise. Thus, option B captures the essence of the passage as it succinctly summarizes the main idea.
3. An object with a charge of 4 μC is placed 50 cm from another object with a charge twice as great. What is the magnitude of the resulting repulsive force?
- A. 0.1152 N
- B. 1.152 N
- C. 10^−3 N
- D. 2.5 × 10^−3 N
Correct answer: D
Rationale: The force between two charges is calculated using Coulomb's Law, which states that the force is proportional to the product of the two charges and inversely proportional to the square of the distance between them. Given that one charge is twice as great as the other and the distance between them is 50 cm, we can calculate the repulsive force. The magnitude of the resulting repulsive force is 2.5 × 10^−3 N. Choice A is incorrect as it does not match the calculated value. Choice B is incorrect as it is significantly higher than the correct answer. Choice C is incorrect as it represents 10^−3 N, which is lower than the calculated value.
4. Subtract 12 1/8 - 9 1/2.
- A. 2 5/8
- B. 3 1/8
- C. 4 1/2
- D. 4 2/3
Correct answer: A
Rationale: To subtract mixed numbers, first subtract the fractions: 1/8 - 1/2 = -3/8. Then, subtract the whole numbers: 12 - 9 = 3. Combine the whole number and fraction: 3 - 3/8 = 2 5/8. Therefore, the correct answer is A. Choice B is incorrect because it does not reflect the correct subtraction of the fractions. Choices C and D are incorrect as they do not result from the correct subtraction process outlined above.
5. Aluminum (Al) has 13 protons in its nucleus. What is the number of electrons in an Al3+ ion?
- A. 16
- B. 13
- C. 10
- D. 3
Correct answer: C
Rationale: Aluminum (Al) has an atomic number of 13, which indicates it normally has 13 electrons to balance the 13 protons in its nucleus. When Al forms an Al3+ ion, it loses 3 electrons to achieve a stable electron configuration. Therefore, the Al3+ ion will have 13 - 3 = 10 electrons. Choice A (16) is incorrect as it doesn't take into account the charge of the Al3+ ion. Choice B (13) is incorrect because the Al3+ ion has lost electrons. Choice D (3) is incorrect as it doesn't reflect the total number of electrons lost by the Al atom to form the Al3+ ion.
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