HESI A2
HESI A2 Chemistry Questions
1. Which element has the chemical symbol 'Fe'?
- A. Lead
- B. Iron
- C. Silver
- D. Copper
Correct answer: B
Rationale: The correct answer is 'Iron' as it has the chemical symbol 'Fe'. Chemical symbols are used to represent elements in the periodic table, and 'Fe' specifically refers to Iron. Choice A, Lead, is incorrect as the chemical symbol for Lead is 'Pb'. Choice C, Silver, is incorrect as the chemical symbol for Silver is 'Ag'. Choice D, Copper, is incorrect as the chemical symbol for Copper is 'Cu'. Therefore, 'Iron' is the only element among the choices with the chemical symbol 'Fe'.
2. How many neutrons are in an atom of carbon-12?
- A. 2
- B. 4
- C. 6
- D. 24
Correct answer: C
Rationale: An atom of carbon-12 has 6 neutrons. The atomic number of carbon is 6, representing the number of protons. The atomic mass of carbon-12 is 12. To find the number of neutrons, subtract the atomic number from the atomic mass: 12 - 6 = 6 neutrons. Choice A, 2, is incorrect as it does not reflect the correct calculation for neutrons in carbon-12. Choice B, 4, is incorrect as it does not match the correct number of neutrons in carbon-12. Choice D, 24, is incorrect as it is significantly higher than the actual number of neutrons in carbon-12.
3. Which intermolecular force is the strongest?
- A. Dipole interactions
- B. Dispersion forces
- C. Hydrogen bonding
- D. Van der Waals forces
Correct answer: C
Rationale: Hydrogen bonding is the strongest intermolecular force due to its specific interaction between a hydrogen atom and a highly electronegative atom like nitrogen, oxygen, or fluorine. This type of bonding results in a very strong attraction between molecules, making it the strongest intermolecular force among the options provided. Dipole interactions (choice A) are weaker than hydrogen bonding as they occur between polar molecules. Dispersion forces (choice B) are the weakest intermolecular forces and are caused by temporary fluctuations in electron distribution. Van der Waals forces (choice D) are a broader term that encompasses dipole interactions and dispersion forces, making them weaker than hydrogen bonding.
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 the correct formula for sodium nitrate?
- A. NaNO
- B. Na NO
- C. NaNO₃
- D. Na NOâ‚‚
Correct answer: C
Rationale: The correct formula for sodium nitrate is NaNO₃. In this formula, 'Na' represents sodium, 'N' represents nitrogen, and 'O₃' represents three oxygen atoms. Sodium nitrate consists of one sodium ion (Naâº) and one nitrate ion (NO₃â»), which means the correct formula is NaNO₃. Choice A (NaNO) is incorrect as it lacks the subscript indicating the presence of three oxygen atoms. Choice B (Na NO) is incorrect as it includes a space between 'Na' and 'NO', which is not part of the standard chemical formula notation. Choice D (Na NOâ‚‚) is incorrect as it indicates a different compound with a nitrite ion (NOâ‚‚â») instead of nitrate ion.
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