HESI A2
Chemistry HESI A2 Practice Test
1. What is the correct name of AgNO₃?
- A. Argent nitrous
- B. Argent oxide
- C. Silver nitrite
- D. Silver nitrate
Correct answer: D
Rationale: The correct name for AgNO₃ is silver nitrate. In chemical nomenclature, the element symbol Ag represents silver, and the polyatomic ion NO₃ is known as nitrate. Therefore, when the silver ion (Ag⁺) combines with the nitrate ion (NO₃⁻), the resulting compound is named silver nitrate (AgNO₃). Choices A, B, and C are incorrect because they do not accurately represent the composition of AgNO₃. Argent nitrous (Choice A) and Argent oxide (Choice B) do not reflect the correct anion, and Silver nitrite (Choice C) uses a different anion altogether.
2. You contain two odorous gases in vials with porous plugs. Gas A has twice the mass of Gas B. Which observation is most likely?
- A. You will smell Gas A before you smell Gas B.
- B. You will smell Gas B before you smell Gas A.
- C. You will smell Gas A but not Gas B.
- D. You will smell Gas B but not Gas A.
Correct answer: A
Rationale: The rate of effusion of a gas is inversely proportional to the square root of its molar mass. Since Gas A has twice the mass of Gas B, Gas A will effuse more slowly than Gas B. Therefore, you will likely smell Gas A before you smell Gas B as Gas A will escape and diffuse through the porous plug at a slower rate compared to Gas B. Choice A is correct because Gas A, with its higher molar mass, will take longer to effuse through the porous plug, causing you to smell it first. Choices B, C, and D are incorrect as they do not consider the relationship between molar mass and effusion rate.
3. In which state of matter are particles packed tightly together in a fixed position?
- A. Liquid
- B. Solid
- C. Gas
- D. Plasma
Correct answer: B
Rationale: In a 'solid' state, particles are tightly packed in fixed positions, maintaining a definite shape and volume. This arrangement allows solids to maintain a rigid structure. Liquids have particles that are close together but can move past each other, giving them the ability to flow and take the shape of their container. Gases have particles that are far apart and move freely, leading to their ability to expand to fill any container. Plasma is an ionized gas where particles have high energy levels and are not packed tightly together, making it an uncommon state of matter on Earth.
4. Which of the following is a property of an acid?
- A. Bitter taste
- B. Slippery feel
- C. Reacts with bases
- D. Sweet taste
Correct answer: C
Rationale: The correct property of an acid is that it 'reacts with bases.' Acids are known for their ability to react with bases to form salts and water through a process called neutralization. This unique reaction distinguishes acids from other substances and is a fundamental characteristic of acids in chemistry. Choices A, B, and D are incorrect. Acids do not have a bitter taste (Choice A), a slippery feel (Choice B), or a sweet taste (Choice D). These properties are not typical of acids and may lead to confusion if associated with acids.
5. What is another name for aqueous HI?
- A. hydroiodic acid
- B. hydrogen monoiodide
- C. hydrogen iodide
- D. hydriodic acid
Correct answer: D
Rationale: The correct name for aqueous HI is 'hydriodic acid.' When hydrogen iodide (HI) dissolves in water, it forms hydriodic acid. Therefore, 'hydriodic acid' is the appropriate term for aqueous HI. Choice A, 'hydroiodic acid,' is incorrect as it does not reflect the nature of the compound in the aqueous state. Choice B, 'hydrogen monoiodide,' is not a widely recognized term for this compound. Choice C, 'hydrogen iodide,' is the name for HI in the gaseous state, not when it's dissolved in water.
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