HESI A2
Chemistry HESI A2 Practice Test
1. Which is a property of an ionic compound?
- A. Low melting point
- B. Poor conductivity
- C. Shared electrons
- D. Crystalline shape
Correct answer: D
Rationale: Ionic compounds are composed of positively and negatively charged ions that are held together by strong electrostatic forces. These ions arrange themselves in a repeating pattern to form a stable and orderly structure known as a crystalline shape. This is a characteristic property of ionic compounds, making choice D the correct answer. Choices A, B, and C are incorrect because ionic compounds typically have high melting points, good conductivity in the molten or dissolved state, and do not involve shared electrons but rather the transfer of electrons between atoms.
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 net charge of an ionic compound?
- A. 0
- B. -1
- C. +1
- D. Variable
Correct answer: A
Rationale: The correct answer is A: 0. Ionic compounds have a net charge of 0 because they are formed by the combination of positively charged ions (cations) and negatively charged ions (anions) in a way that neutralizes their charges. This balanced combination results in an electrically neutral compound. Therefore, the net charge of an ionic compound is typically 0. Choices B, C, and D are incorrect because ionic compounds are designed to have a total neutral charge, with the positive charges balancing out the negative charges.
4. How much concentrated HCl should be used to prepare 500 mL of a 0.100 M HCl solution?
- A. 75 mL
- B. 100 mL
- C. 125 mL
- D. 150 mL
Correct answer: B
Rationale: To prepare a 0.100 M HCl solution with a volume of 500 mL, you can use the formula C1V1 = C2V2, where C1 is the concentration of the concentrated HCl solution, V1 is the volume of concentrated HCl solution used, C2 is the desired concentration (0.100 M), and V2 is the final volume (500 mL). Rearranging the formula to solve for V1, you get V1 = (C2V2) / C1. Plugging in the values (0.100 M)(500 mL) / C1 = 100 mL, which means 100 mL of concentrated HCl should be used to prepare 500 mL of a 0.100 M HCl solution. Therefore, the correct answer is 100 mL. Choice A (75 mL), Choice C (125 mL), and Choice D (150 mL) are incorrect as they do not match the calculated volume needed to prepare the desired concentration of HCl solution.
5. What are neutral particles called?
- A. Neutrons
- B. Protons
- C. Electrons
- D. Cations
Correct answer: A
Rationale: Neutral particles, which have no electric charge, are known as neutrons. Neutrons are found in the nucleus of an atom along with protons. Electrons carry a negative charge and orbit the nucleus. Cations are positively charged ions formed by losing electrons. Therefore, the correct answer is 'Neutrons' as they are the neutral particles in an atom, unlike protons, electrons, or cations.
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