Chemistry HESI A2 Practice Test

Correct Answer: C

Rationale: The correct answer is C: 11. Alkali metals are found in Group 1 of the periodic table, which includes elements like sodium (Na) and potassium (K). These elements have 11 protons in their atomic nucleus, giving them an atomic number of 11. The number of protons determines the element's identity, so alkali metals always have 11 protons. Choices A, B, and D are incorrect as they do not correspond to the characteristic number of protons for alkali metals.

Correct Answer: B

Rationale: The correct answer is B: < 7. Acids have a pH below 7 because they release hydrogen ions when dissolved in water, making the solution acidic. A pH of 7 is neutral, not acidic. Choices A (7.5) and C (> 7) are incorrect because they indicate values above 7, which would be alkaline/basic. Choice D (7) is incorrect because it represents a neutral pH, not acidic. Thus, the correct answer is B as it accurately represents the pH range of acids.

Correct Answer: A

Rationale: To balance the equation, count the number of O atoms on both sides. If the equation is balanced, the coefficient of O should be the same on both sides. In this case, the coefficient of O is already 1 on both sides (since O appears only once on each side), so the correct answer is A. Choices B, C, and D are incorrect because changing the coefficient of O to any of those values would unbalance the equation.

Correct Answer: C

Rationale: The correct answer is C: 11. Alkali metals are found in Group 1 of the periodic table, which includes elements like sodium (Na) and potassium (K). These elements have 11 protons in their atomic nucleus, giving them an atomic number of 11. The number of protons determines the element's identity, so alkali metals always have 11 protons. Choices A, B, and D are incorrect as they do not correspond to the characteristic number of protons for alkali metals.

Correct Answer: C

Rationale: The correct answer is C: Fluorine. Fluorine is not an allotrope of carbon because allotropes are different forms of the same element. Fluorine is a different element altogether. Diamond, graphite, and buckminsterfullerene are all allotropes of carbon, each with unique molecular structures and properties. Diamond has a tetrahedral structure, graphite has layers of hexagonal rings, and buckminsterfullerene has a spherical shape. Fluorine, on the other hand, is a diatomic molecule consisting of two atoms of fluorine bonded together. Therefore, C is the correct answer as it does not belong to the category of carbon allotropes.