HESI A2
HESI A2 Chemistry Practice Questions
1. Which one does not name a polar molecule?
- A. NH₃
- B. H₂S
- C. SO₂
- D. CO₂
Correct answer: A
Rationale: The correct answer is NH₃. The molecule NH₃ does not represent a polar molecule because nitrogen and hydrogen in this molecule have a small difference in electronegativity that does not result in a significant polar covalent bond. In contrast, molecules H₂S, SO₂, and CO₂ have polar covalent bonds due to larger electronegativity differences, making them polar molecules. Therefore, options B, C, and D are polar molecules, unlike option A.
2. Which statement is true of a saturated solution?
- A. It has more solute than can dissolve in the solvent.
- B. It has less solute that can dissolve in the solvent.
- C. It has the maximum concentration of the solute dissolved in the solvent.
- D. It contains a precipitate that lowers the concentration of the solute in the solvent.
Correct answer: C
Rationale: A saturated solution contains the maximum concentration of solute that can be dissolved in a specific amount of solvent at a particular temperature. Once a solution is saturated, adding more solute will not increase its concentration since the excess solute will not dissolve and will instead form a precipitate, indicating that the solution is at its maximum capacity. Choices A, B, and D are incorrect because a saturated solution has reached its limit in dissolving solute, so it cannot contain more solute than it can dissolve (choice A), less solute than it can dissolve (choice B), or a precipitate that lowers the concentration of the solute in the solvent (choice D).
3. What is the charge of a beta particle?
- A. -1
- B. +1
- C. +2
- D. No charge
Correct answer: A
Rationale: A beta particle has a charge of -1. Beta particles are high-energy, high-speed electrons emitted during radioactive decay processes. Since electrons carry a charge of -1, beta particles also carry a charge of -1. This negative charge indicates that beta particles are negatively charged. Option B is incorrect as it suggests a positive charge, which is not the case for beta particles. Option C is incorrect as it indicates a higher positive charge, which is not true for beta particles. Option D is incorrect as beta particles do have a charge, which is negative.
4. Which of the following represents a hydride ion?
- A. H⁻
- B. H⁺
- C. OH⁻
- D. HCl
Correct answer: A
Rationale: The hydride ion is denoted by H⁻, indicating that it has gained an extra electron to complete its valence shell, resulting in a full octet and a net charge of -1. This ion is commonly found in metal hydrides and plays a significant role in various chemical reactions. Option B, H⁺, represents a proton with a positive charge. Option C, OH⁻, represents the hydroxide ion, consisting of oxygen and hydrogen. Option D, HCl, is a compound composed of hydrogen and chlorine ions, not a hydride ion.
5. How many moles of potassium bromide are in 25 mL of a 4 M KBr solution?
- A. 0.035 mol
- B. 0.1 mol
- C. 0.18 mol
- D. 1.6 mol
Correct answer: B
Rationale: To find the moles of potassium bromide in 25 mL of a 4 M KBr solution, we first need to convert the volume from milliliters to liters. 25 mL is equal to 0.025 L. Then, we use the formula moles = molarity x volume in liters. Substituting the values, moles = 4 M x 0.025 L = 0.1 mol. Therefore, there are 0.1 moles of KBr in 25 mL of a 4 M solution. Choice A, 0.035 mol, is incorrect as it does not properly calculate the moles. Choice C, 0.18 mol, and choice D, 1.6 mol, are also incorrect as they are not the result of the correct calculation based on the given molarity and volume.
Similar Questions
Access More Features
HESI A2 Basic
$49/ 30 days
- 3,000 Questions with answers
- 30 days access @ $49
HESI A2 Premium
$99/ 90 days
- Actual HESI A 2 Questions
- 3,000 questions with answers
- 90 days access @ $99