HESI A2
Chemistry HESI A2 Practice Test
1. Radioactive isotopes are frequently used in medicine. What kind of half-life would a medical isotope probably have?
- A. Seconds-long
- B. Days-long
- C. Years-long
- D. Many years long
Correct answer: B
Rationale: Medical isotopes used in diagnosis and treatment need to have a relatively short half-life to minimize radiation exposure to patients. If the half-life were too long (such as many years) or even years-long, the radiation would persist for too long and could be harmful to the patient. Seconds-long half-lives would not provide enough time for the isotope to be effective. Days-long half-lives strike a balance between providing enough time for the isotope to be used effectively and minimizing radiation exposure.
2. A bottle of hand sanitizer contains 70% alcohol. If 5ml of sanitizer are used, how much pure alcohol is present?
- A. 1.4ml
- B. 2.1ml
- C. 2.8ml
- D. 3.5ml
Correct answer: B
Rationale: Rationale: - If the hand sanitizer contains 70% alcohol, it means that 70% of the 5ml used is pure alcohol. - To find the amount of pure alcohol present, we calculate 70% of 5ml: 0.7 * 5ml = 3.5ml. - Therefore, when 5ml of sanitizer are used, there are 3.5ml of pure alcohol present.
3. Calculate the product of (99)(0.56) =
- A. 99.30
- B. 99.56
- C. 55.44
- D. 199.54
Correct answer: C
Rationale: To find the product of 99 and 0.56, multiply the two numbers: 99 x 0.56 = 55.44. Therefore, the correct answer is 55.44.
4. What is the role of the alveoli in the lungs?
- A. To filter blood
- B. To exchange gases
- C. To transport nutrients
- D. To store oxygen
Correct answer: B
Rationale: The alveoli in the lungs are tiny air sacs responsible for the exchange of oxygen and carbon dioxide during breathing. Oxygen from inhaled air diffuses into the bloodstream through the alveoli, while carbon dioxide produced by cells is removed from the blood and exhaled out of the body through the alveoli. This gas exchange process is essential for the body to obtain oxygen and get rid of carbon dioxide, supporting cellular functions and maintaining overall health. Choices A, C, and D are incorrect because the alveoli do not filter blood, transport nutrients, or store oxygen. Their main function is gas exchange.
5. What is the primary function of the lymphatic system?
- A. Transport oxygen to cells
- B. Remove carbon dioxide from the body
- C. Produce hormones
- D. Transport nutrients
Correct answer: B
Rationale: The correct answer is B: Remove carbon dioxide from the body. The primary function of the lymphatic system is to return excess tissue fluid to the bloodstream and assist in the body's defense against infections by filtering out harmful pathogens and foreign particles. Choices A, C, and D are incorrect because transporting oxygen to cells is mainly done by the circulatory system, hormone production is primarily carried out by endocrine glands, and nutrient transport is also a function of the circulatory system and the digestive system, not the lymphatic system.
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