HESI A2
Chemistry HESI A2 Practice Test
1. What is an alloy in which another metal is dissolved in mercury (Hg) called?
- A. Electrum
- B. Amalgam
- C. Solder
- D. Bronze
Correct answer: B
Rationale: An amalgam is a type of alloy where another metal is dissolved in mercury (Hg). This process forms a unique mixture that has various applications in dentistry, chemistry, and other fields. Electrum is a natural alloy of gold and silver, solder is a metal alloy used to join other metals together, and bronze is a copper-tin alloy. Therefore, the correct answer is B - Amalgam.
2. What does a blood sample with a pH of 3 indicate?
- A. It is strongly acidic.
- B. It is strongly basic.
- C. It is weakly acidic.
- D. It is weakly basic.
Correct answer: A
Rationale: A blood pH of 3 is significantly low, indicating a strong acidity level. The normal blood pH range is 7.35 to 7.45; therefore, a pH of 3 is far below the normal range, showing a highly acidic condition in the blood sample. Choice B is incorrect because a pH of 3 is not basic at all. Choice C is incorrect as a pH of 3 is not weakly acidic but strongly acidic. Choice D is wrong as a blood pH of 3 does not indicate a weakly basic condition.
3. Which compound is a Hydrogen or proton donor, corrosive to metals, causes blue litmus paper to become red, and becomes less acidic when mixed with a base?
- A. Base
- B. Acid
- C. Salt
- D. Hydroxide
Correct answer: B
Rationale: The correct answer is 'Acid.' An acid is a compound that donates protons (H+), is corrosive to metals, and turns blue litmus paper red. When an acid is mixed with a base, they react to form salts and water, resulting in a decrease in acidity. Choices A, C, and D are incorrect because bases accept protons rather than donate them, salts are the products of acid-base reactions, and hydroxides are typically bases, not acids.
4. What is the primary function of enzymes?
- A. To provide energy for reactions
- B. To speed up reactions
- C. To decrease activation energy
- D. To act as a catalyst
Correct answer: B
Rationale: Enzymes function to speed up reactions by lowering the activation energy required for the reaction to occur. They act as biological catalysts, providing an alternative pathway for the reaction to proceed more rapidly without being consumed in the process. Choices A, C, and D are incorrect because enzymes do not provide energy for reactions (they do not generate energy), their primary function is not to decrease activation energy (though they do lower it), and while they act as catalysts, the primary function is to speed up reactions by lowering activation energy.
5. What is the SI unit of energy?
- A. ohm
- B. joule
- C. henry
- D. newton
Correct answer: B
Rationale: The SI unit of energy is the 'joule'. The joule is defined as the work done when a force of one newton acts over a distance of one meter. It is the standard unit used to measure energy in the International System of Units (SI). Therefore, the correct answer is 'joule.' Choice A, 'ohm,' is the SI unit of electrical resistance, not energy. Choice C, 'henry,' is the SI unit of inductance, not energy. Choice D, 'newton,' is the SI unit of force, not energy. Hence, they are all incorrect in the context of measuring energy.
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