HESI A2

1. Question 1 · Mathematics

   A child who weighs 44 lb is prescribed an antibiotic at 7.5 mg/kg per dose. The suspension on hand contains 50 mg per 5 mL. How many milliliters should be given per dose?
   • A.33 mL
   • B.6.6 mL
   • C.15 mL
   • D.1.5 mL
   Show answer and explanation

   Answer: C. 15 mL

   Convert weight: 44 ÷ 2.2 = 20 kg. Dose: 20 × 7.5 = 150 mg. Volume: 150 mg ÷ 50 mg × 5 mL = 15 mL. Using 44 as if it were kilograms gives 33 mL.

2. Question 2 · Reading Comprehension

   Based on the passage, why did infection rates rise in some hospitals after anesthesia was introduced?
   • A.Ether and chloroform weakened patients' natural immune defenses.
   • B.Surgeons abandoned antiseptic methods in favor of greater speed.
   • C.Longer operations left patients' wounds exposed for more time.
   • D.Sleeping patients could not report the early signs of infection.
   Show answer and explanation

   Answer: C. Longer operations left patients' wounds exposed for more time.

   The passage links the rise directly to the fact that operations could last longer, so wounds stayed open longer. Antiseptic methods were adopted only later, so they could not have been abandoned, and the passage never says the anesthetics affected immunity.

3. Question 3 · Vocabulary and General Knowledge

   Select the meaning of the bold word in the sentence: A blood clot can occlude a coronary artery and deprive the heart muscle of oxygen.
   • A.widen
   • B.rupture
   • C.weaken
   • D.block
   Show answer and explanation

   Answer: D. block

   To occlude is to close off or obstruct a passage. A blocked coronary artery stops blood flow, which is why the heart muscle loses its oxygen supply.

4. Question 4 · Grammar

   Which sentence uses a colon correctly?
   • A.Bring the following supplies: gauze, tape, and saline.
   • B.The dressing kit contains: gauze, tape, and saline.
   • C.Please bring: gauze, tape, and saline to the room.
   • D.The supplies we need are: gauze, tape, and saline.
   Show answer and explanation

   Answer: A. Bring the following supplies: gauze, tape, and saline.

   A colon should follow a complete independent clause, such as "Bring the following supplies." A colon should not separate a verb (contains, bring, are) from its object or complement.

5. Question 5 · Chemistry

   Technetium-99m has a half-life of 6 hours. A patient receives a dose containing 80 mg of Tc-99m. How much remains after 24 hours?
   • A.10 mg
   • B.20 mg
   • C.0 mg
   • D.5 mg
   Show answer and explanation

   Answer: D. 5 mg

   24 hours ÷ 6 hours = 4 half-lives. 80 → 40 → 20 → 10 → 5 mg, or 80 × (1/2)⁴ = 5 mg. The value 10 mg stops after only 3 half-lives.

6. Question 6 · Mathematics

   A patient is ordered heparin 7,500 units subcutaneously. The vial is labeled 10,000 units/mL. How many milliliters should the nurse draw up?
   • A.0.75 mL
   • B.1.33 mL
   • C.0.075 mL
   • D.7.5 mL
   Show answer and explanation

   Answer: A. 0.75 mL

   Dose ÷ concentration: 7,500 ÷ 10,000 = 0.75 mL. Inverting the fraction (10,000 ÷ 7,500) gives 1.33 mL.

7. Question 7 · Vocabulary and General Knowledge

   As used in paragraph 1, the word obscures most nearly means
   • A.clarifies
   • B.exaggerates
   • C.disproves
   • D.conceals
   Show answer and explanation

   Answer: D. conceals

   The popular "Lady with the Lamp" image draws attention away from her statistical work, keeping it hidden. The image is called accurate, so it does not disprove anything, and it certainly does not clarify her other contribution.

8. Question 8 · Vocabulary and General Knowledge

   Select the meaning of the bold word in the sentence: Although he was confused during the night, the patient was lucid when the physician visited in the morning.
   • A.thinking clearly
   • B.deeply asleep
   • C.visibly agitated
   • D.unusually talkative
   Show answer and explanation

   Answer: A. thinking clearly

   Lucid means mentally clear and able to think rationally. The word "although" contrasts his clear thinking in the morning with his confusion at night.

9. Question 9 · Vocabulary and General Knowledge

   Select the word that correctly completes the sentence: The ___ reason for the delay in surgery was a shortage of operating-room staff.
   • A.principle
   • B.principals
   • C.principle's
   • D.principal
   Show answer and explanation

   Answer: D. principal

   Principal as an adjective means main or most important. Principle is a noun meaning a rule or fundamental truth.

10. Question 10 · Chemistry

    The carbonic acid–bicarbonate system buffers human blood. When lactic acid adds H⁺ to the blood during exercise, which reaction limits the drop in pH?
    • A.H₂CO₃ releases H⁺ and forms HCO₃⁻.
    • B.Cl⁻ accepts H⁺ and forms HCl.
    • C.HCO₃⁻ accepts H⁺ and forms H₂CO₃.
    • D.Na⁺ accepts H⁺ and forms NaH.
    Show answer and explanation

    Answer: C. HCO₃⁻ accepts H⁺ and forms H₂CO₃.

    Bicarbonate is the conjugate base in the buffer, so it binds added H⁺ to form weak carbonic acid, which can then be exhaled as CO₂. Carbonic acid releasing H⁺ is the buffer's response to added base, not acid.

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