HESI A2
Chemistry HESI A2 Practice Test
1. Which two functional groups would you expect an amino acid to contain?
- A. R-NH2 and R-COOH
- B. R-CHO and R-CO-NH
- C. R-OH and R-COOR
- D. R-O-R and R-COOH
Correct answer: A
Rationale: Amino acids are organic compounds that are characterized by the presence of an amino group (NH2) and a carboxylic acid group (COOH) in their chemical structure. These two functional groups, found in option A, are fundamental components of amino acids and play crucial roles in their classification and biological functions. Option B contains an aldehyde group (CHO) and an amide group (CO-NH), which are not characteristic functional groups of amino acids. Option C includes a hydroxyl group (OH) and an ester group (COOR), which are not typically present in amino acids. Option D presents ether (R-O-R) and carboxylic acid (COOH) functional groups, which do not represent the functional groups commonly found in amino acids.
2. Which one is not a hydrocarbon?
- A. Methane (CH4)
- B. Pyridine (C5H5N)
- C. Ethane (C2H6)
- D. Propane (C3H8)
Correct answer: B
Rationale: The correct answer is B, Pyridine (C5H5N). Pyridine is not a hydrocarbon because it contains nitrogen (N) in its molecular structure, in addition to carbon (C) and hydrogen (H) atoms. Hydrocarbons consist solely of carbon and hydrogen atoms. Methane (CH4), ethane (C2H6), and propane (C3H8) are all examples of hydrocarbons as they only contain carbon and hydrogen atoms, making them organic compounds known for their combustion properties.
3. Which material has the smallest specific heat capacity?
- A. water
- B. wood
- C. aluminum
- D. glass
Correct answer: C
Rationale: Specific heat capacity is the amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius. Among the options provided, aluminum has the smallest specific heat capacity. This means that it requires the least amount of heat to raise its temperature compared to water, wood, and glass. Water has a high specific heat capacity, making it resistant to temperature changes, while wood and glass have higher specific heat capacities compared to aluminum.
4. What are bases or alkaline solutions known as?
- A. Hydrogen acceptors
- B. Solutions of low pH
- C. Hydrogen donors
- D. Amphoteric
Correct answer: A
Rationale: Bases or alkaline solutions are known as 'hydrogen acceptors.' They accept protons (H+) in chemical reactions, as opposed to acids that donate protons. This property allows bases to neutralize acids and form salts. Choice B, 'Solutions of low pH,' is incorrect because bases have high pH values, not low. Choice C, 'Hydrogen donors,' is incorrect as bases do not donate protons but accept them. Choice D, 'Amphoteric,' refers to substances that can act as both acids and bases, which is not the definition of bases. Therefore, the correct answer is A.
5. What is the correct formula for potassium chloride?
- A. NaCl
- B. KCl
- C. KCl
- D. ClK
Correct answer: B
Rationale: The correct formula for potassium chloride is KCl. In chemical formulas, the symbol for the cation (positive ion) comes first followed by the symbol for the anion (negative ion). Potassium is represented by the symbol K, while chloride is represented by the symbol Cl. Therefore, the formula for potassium chloride is KCl. Choice A (NaCl) is the formula for sodium chloride, not potassium chloride. Choice C is a duplicate of choice B, and choice D (ClK) is an incorrect arrangement of the symbols for potassium and chloride.
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