Nursing Elites

1. What is the correct formula for calcium carbonate?

• A. CaSO₃
• B. CaCO₃
• C. Ca(OH)₂
• D. CH₃OH

Correct answer: B

Rationale: The correct formula for calcium carbonate is CaCO₃, which consists of one calcium (Ca) atom, one carbon (C) atom, and three oxygen (O) atoms. Therefore, choice B, CaCO₃, is the accurate formula for calcium carbonate. Choices A, C, and D do not represent the correct formula for calcium carbonate. Choice A, CaSO₃, is calcium sulfite, not calcium carbonate. Choice C, Ca(OH)₂, is calcium hydroxide, and choice D, CH₃OH, is methanol, none of which are correct formulas for calcium carbonate.

2. What is the oxidation state of the chlorine atom in the compound HCl?

• A. +1
• B. -1
• C. +2
• D. -2

Correct answer: B

Rationale: In the compound HCl (hydrochloric acid), the hydrogen atom has an oxidation state of +1 based on the rules of assigning oxidation states. Since the overall compound is neutral, the oxidation state of chlorine must be -1 to balance the charge. Chlorine typically has an oxidation state of -1 in binary compounds with nonmetals, such as HCl. Therefore, the correct answer is -1. Choices A, C, and D are incorrect as the oxidation state of chlorine in HCl is -1, not +1, +2, or -2.

3. What is the charge of noble gases?

• A. -1
• B. 0
• C. 1
• D. 2

Correct answer: B

Rationale: The correct answer is B: 0. Noble gases have a charge of 0 because they have full valence shells and are inert. This makes them stable and unreactive, resulting in a charge of 0 as they do not readily gain or lose electrons. Choices A, C, and D are incorrect because noble gases do not typically form ions by gaining or losing electrons, so they do not carry a charge of -1, 1, or 2.

4. What is the correct name of MgO?

• A. Manganese oxide
• B. Magnesium oxide
• C. Magnesium oxate
• D. Magnesium hydroxide

Correct answer: B

Rationale: The correct name of MgO is Magnesium oxide. Mg represents the chemical symbol for magnesium, and O represents the chemical symbol for oxygen. When these elements combine, they form magnesium oxide. Option A, Manganese oxide, is incorrect as it refers to a compound of manganese and oxygen, not magnesium. Option C, Magnesium oxate, is not a valid chemical compound name. Option D, Magnesium hydroxide, refers to a different compound consisting of magnesium, oxygen, and hydrogen.

5. How many times more acidic is a substance with a pH of 3 compared to a substance with a pH of 5?

• A. 8
• B. 2
• C. 100
• D. 1,000

Correct answer: D

Rationale: The pH scale is logarithmic, indicating that each pH unit change reflects a 10-fold difference in acidity level. Going from pH 5 to pH 3 involves a difference of 2 units, which translates to a 100-fold increase in acidity level (10^2 = 100 for each unit). Therefore, a substance with a pH of 3 is 1,000 times more acidic than a substance with a pH of 5 (100 * 10 = 1,000). Choice A (8) is incorrect as it does not consider the logarithmic nature of the pH scale. Choice B (2) is incorrect because it represents the difference in pH units, not the increase in acidity level. Choice C (100) is incorrect as it miscalculates the increase in acidity level, which is 1,000 times and not 100 times.

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