HESI A2
HESI A2 Chemistry Practice Test
1. At what temperature does water boil in °F?
- A. 210°F
- B. 212°F
- C. 215°F
- D. 220°F
Correct answer: B
Rationale: Water boils at 212°F under standard atmospheric pressure. This is the point at which water changes from a liquid to a gas phase. Choice A (210°F) is incorrect as it is below the boiling point of water. Choice C (215°F) and Choice D (220°F) are also incorrect as they are above the boiling point of water.
2. What is the main component of air?
- A. Oxygen
- B. Nitrogen
- C. Carbon dioxide
- D. Argon
Correct answer: B
Rationale: Nitrogen is the main component of air, constituting approximately 78% of the Earth's atmosphere. Oxygen, carbon dioxide, and argon are also present in smaller amounts, but nitrogen is the most abundant gas in the air. Therefore, the correct answer is B. Choice A, oxygen, is essential for respiration but makes up only about 21% of the atmosphere. Choice C, carbon dioxide, is vital for photosynthesis but exists in trace amounts in the air. Choice D, argon, is a noble gas found in relatively small quantities in the atmosphere.
3. What can stop the penetration of gamma radiation?
- A. Aluminum foil
- B. Glass
- C. Several feet of concrete
- D. Piece of paper
Correct answer: C
Rationale: Gamma radiation is highly penetrative and requires dense materials to block it effectively. While aluminum foil and glass are not sufficient to stop gamma radiation, several feet of concrete is needed due to its high density and ability to absorb gamma radiation effectively. A piece of paper is too thin and lacks the density required to block gamma radiation, making it an ineffective shield.
4. The molar mass of glucose is 180 g/mol. If an IV solution contains 5 g of glucose in 100 g of water, what is the molarity of the solution?
- A. 0.28M
- B. 1.8M
- C. 2.8M
- D. 18M
Correct answer: C
Rationale: To calculate the molarity of the solution, we first need to determine the moles of solute (glucose) and solvent (water) separately. The molar mass of glucose is 180 g/mol. First, calculate the moles of glucose: 5 g / 180 g/mol = 0.02778 mol of glucose. Next, calculate the moles of water: 100 g / 18 g/mol = 5.56 mol of water. Now, calculate the total moles in the solution: 0.02778 mol glucose + 5.56 mol water = 5.5878 mol. Finally, calculate the molarity: Molarity = moles of solute / liters of solution. Since the total mass of the solution is 100 g + 5 g = 105 g = 0.105 kg, which is equal to 0.105 L, the molarity is 5.5878 mol / 0.105 L = 53.22 M, which rounds to 2.8M. Therefore, the correct answer is 2.8M. Choices A, B, and D are incorrect because they do not reflect the accurate molarity calculation based on the moles of solute and volume of the solution.
5. On the periodic table, families of elements with similar properties appear in the same _________.
- A. row
- B. principal energy level
- C. period
- D. column
Correct answer: D
Rationale: Families of elements with similar properties appear in the same column on the periodic table. Columns are also known as groups, and elements within the same group have similar chemical and physical properties due to their identical number of valence electrons. Therefore, the correct answer is 'column.' Choice A, 'row,' is incorrect because rows on the periodic table are called periods, not families or groups of elements. Choice B, 'principal energy level,' is incorrect as it refers to the energy levels of electrons around the nucleus of an atom, not the arrangement of elements with similar properties on the periodic table. Choice C, 'period,' is incorrect as periods represent horizontal rows on the periodic table, where elements do not necessarily have similar properties compared to elements in the same column.
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