HESI A2
Chemistry Hesi A2
1. What is the correct electron configuration for carbon?
- A. 1s²2s²2p¹
- B. 1s²2s²2p²
- C. 1s²2s²2p³
- D. 1s²2s²2p⁶3s¹
Correct answer: B
Rationale: The correct electron configuration for carbon is 1s²2s²2p². This configuration indicates that there are 2 electrons in the first energy level (1s²), 2 electrons in the second energy level (2s²), and 2 electrons in the second energy level (2p²). It adheres to the aufbau principle, which states that electrons fill orbitals starting from the lowest energy level, and the Pauli exclusion principle, which states that each electron in an atom must have a unique set of quantum numbers. Choice A is incorrect because it does not fill the 2p orbital correctly. Choice C is incorrect as it exceeds the number of possible electrons in the 2p orbital. Choice D is incorrect as it includes an electron in the 3s orbital, which is not part of the electron configuration for carbon.
2. Where is a herniated lumbar disc most likely to cause pain?
- A. Along the radial nerve
- B. Within the spinal cord
- C. Along the sciatic nerve
- D. Along the tibial nerve
Correct answer: C
Rationale: A herniated lumbar disc is most likely to cause pain along the sciatic nerve. The sciatic nerve is a long nerve that extends from the lower back down the back of each leg. Compression of the sciatic nerve by a herniated disc can lead to symptoms such as pain, numbness, tingling, or weakness that radiates down the leg. This condition is commonly referred to as sciatica. Choices A, B, and D are incorrect because a herniated lumbar disc typically affects the sciatic nerve, not the radial nerve, spinal cord, or tibial nerve.
3. In this passage, which of these is not mentioned as a possible sign of heat exhaustion?
- A. Dizziness
- B. Nausea
- C. Headache
- D. Drowsiness
Correct answer: D
Rationale: The passage mentions dizziness, nausea, and headache as symptoms but does not list drowsiness.
4. What is tepid bathwater?
- A. Water that is salty
- B. Water that is lukewarm
- C. Water that is icy
- D. Water that is half-full
Correct answer: B
Rationale: Tepid bathwater refers to water that is neither too hot nor too cold, but rather lukewarm in temperature. It is a comfortable and soothing temperature for bathing or soaking. Choice A is incorrect because tepid water is not salty. Choice C is incorrect because icy water is cold, not tepid. Choice D is incorrect as half-full refers to the quantity of water, not its temperature.
5. A radioactive isotope has a half-life of 20 years. How many grams of a 6-gram sample will remain after 40 years?
- A. 8
- B. 6
- C. 3
- D. 1.5
Correct answer: C
Rationale: The half-life of a radioactive isotope is the time it takes for half of the original sample to decay. After each half-life period, half of the initial sample remains. In this case, after the first 20 years, half of the 6-gram sample (3 grams) will remain. After another 20 years (total of 40 years), half of the remaining 3 grams will remain, which is 1.5 grams. Therefore, 3 grams will be left after 40 years. Choice A is incorrect as it doesn't consider the concept of half-life and incorrectly suggests an increase in the sample. Choice B is incorrect as it assumes no decay over time. Choice D is incorrect as it miscalculates the remaining amount after two half-life periods.
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