HESI A2 Chemistry

Correct Answer: D

Rationale: The correct answer is D: ionization energy. Ionization energy is the energy needed to remove an electron from an atom. The outermost electron requires the least amount of energy to remove as it is farthest from the nucleus. This process results in the formation of a positively charged ion. Explanation: 1. Covalent bonding (A) refers to the sharing of electrons between atoms, not the energy required to remove an electron. 2. Electronegativity (B) is the ability of an atom to attract electrons in a chemical bond, not the energy needed to remove an electron. 3. Atomic radius (C) is the size of an atom, which does not directly relate to the energy required to remove an electron.

Correct Answer: B

Rationale: The correct answer is B: 19 protons. Potassium's atomic number is 19, which represents the number of protons in its nucleus. Protons are positively charged particles in an atom. Option A (18) is incorrect as it does not match the atomic number of Potassium. Options C (20) and D (21) are also incorrect as they do not correspond to Potassium's atomic number. Thus, the correct answer is B (19) based on the periodic table.

Correct Answer: C

Rationale: Failed to generate a rationale after 5 retries.

Correct Answer: B

Rationale: To prepare a 0.100 M solution, we use the formula M1V1 = M2V2. Given M1=concentration of concentrated HCl, V1=volume of concentrated HCl, M2=desired concentration, V2=final volume. Plugging in the values, we get M1(unknown volume) = 0.100 M x 500 mL. Solving for the unknown volume, we find V1 = (0.100 M x 500 mL) / M1. As we want to find the volume of concentrated HCl needed, we isolate V1. Therefore, V1 = 100 mL. This corresponds to choice B as the correct answer. Choices A, C, and D are incorrect as they do not match the calculated volume needed to prepare the 0.100 M HCl solution.

Correct Answer: C

Rationale: The correct answer is C: A 5 carbon sugar. Pentose sugars are carbohydrates with 5 carbon atoms. They are essential components of nucleic acids like DNA and RNA. A is incorrect because it has 6 carbons, not 5. B is incorrect as it has 4 carbons. D is incorrect as it has 7 carbons, not 5. Therefore, the correct choice is C as it accurately describes a pentose sugar.