HESI A2
HESI A2 Chemistry Practice Questions
1. Which of these types of intermolecular force is weakest?
- A. Dipole-dipole interaction
- B. London dispersion force
- C. Hydrogen bonding
- D. Ionic bonding
Correct answer: B
Rationale: The correct answer is B, London dispersion force. London dispersion forces are the weakest type of intermolecular force among the options provided. These forces arise from temporary fluctuations in electron distribution within molecules, leading to temporary dipoles. London dispersion forces are present in all molecules and are generally weaker than dipole-dipole interactions, hydrogen bonding, and ionic bonding. Dipole-dipole interactions are stronger than London dispersion forces as they involve permanent dipoles in molecules. Hydrogen bonding is stronger than both London dispersion and dipole-dipole interactions as it is a special type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen or nitrogen. Ionic bonding is the strongest type of intermolecular force among the options, but it is not the correct answer for the weakest type of force.
2. Which muscle is responsible for breathing?
- A. Diaphragm
- B. Intercostal muscles
- C. Rectus abdominis
- D. Pectoralis major
Correct answer: A
Rationale: The diaphragm is the primary muscle responsible for breathing. It is a large, dome-shaped muscle located at the base of the chest cavity. When it contracts, it flattens, increasing the volume of the chest cavity and causing inhalation. When it relaxes, it returns to its dome shape, decreasing the volume of the chest cavity and causing exhalation. The intercostal muscles, located between the ribs, assist the diaphragm in breathing by expanding and contracting the chest cavity. The rectus abdominis and pectoralis major are not directly involved in the process of breathing.
3. Choose the meaning of the word rationale in the following sentence: "Step-by-step, the doctor explained the rationale for the treatment."
- A. Reasoning
- B. Prescription
- C. Procedure
- D. Necessity
Correct answer: A
Rationale: Corrected Question: In this context, the word 'rationale' refers to the underlying reasoning or justification for the treatment being explained step-by-step by the doctor. It pertains to the logical basis or thought process behind the chosen course of action. 'Prescription' (Choice B), 'Procedure' (Choice C), and 'Necessity' (Choice D) do not accurately capture the meaning of 'rationale' in the sentence provided.
4. A circular bandage has a diameter of 6cm. What is the area covered by the bandage (area of a circle = πr^2)?
- A. 9π cm^2
- B. 18π cm^2
- C. 27π cm^2
- D. 36π cm^2
Correct answer: C
Rationale: Rationale: - The formula for the area of a circle is A = πr^2, where r is the radius of the circle. - The diameter of the circular bandage is 6 cm, so the radius (r) is half of the diameter, which is 6/2 = 3 cm. - Substitute the radius (r = 3 cm) into the formula for the area of a circle: A = π(3)^2 = 9π cm^2. - Therefore, the area covered by the bandage is 9π cm^2.
5. What is the primary function of the digestive system?
- A. To transport oxygen
- B. To break down food and absorb nutrients
- C. To produce hormones
- D. To transport blood
Correct answer: B
Rationale: The primary function of the digestive system is to break down food into smaller molecules and absorb nutrients such as vitamins, minerals, carbohydrates, proteins, and fats. These nutrients are then utilized by the body for energy, growth, and repair. The digestive system plays a crucial role in the process of extracting essential components from food and distributing them to the body's cells through the bloodstream. Choices A, C, and D are incorrect because transporting oxygen, producing hormones, and transporting blood are functions associated with other body systems like the respiratory system, endocrine system, and circulatory system, respectively, not the digestive system.
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