Nursing Elites

1. What is the correct electron configuration for lithium?

• A. 1s²2s¹
• B. 1s²2s²
• C. 1s²2s¹2p¹
• D. 1s¹2s¹2p²

Correct answer: A

Rationale: The electron configuration for lithium is 1s²2s¹. Lithium has 3 electrons, and the configuration indicates that the first two electrons fill the 1s orbital, while the third electron fills the 2s orbital. Therefore, the correct electron configuration for lithium is 1s²2s¹. Choice B (1s²2s²) is incorrect as it represents the electron configuration for beryllium, not lithium. Choice C (1s²2s¹2p¹) includes the 2p orbital, which is not involved in lithium's electron configuration. Choice D (1s¹2s¹2p²) is incorrect as it does not accurately represent lithium's electron configuration.

2. Which of the following substances is a base?

• A. Water
• B. Sodium chloride
• C. Ammonia
• D. Salt

Correct answer: C

Rationale: The correct answer is 'Ammonia' (Choice C) as it is a common example of a base. Bases are substances that release hydroxide ions (OH-) in aqueous solutions, helping to increase the pH level. Ammonia is a weak base that can accept a proton (H+) to form ammonium hydroxide. In contrast, water (Choice A), sodium chloride (Choice B), and salt (Choice D) are not bases; water is neutral, while sodium chloride and salt are neutral compounds composed of a cation and an anion.

3. If 5 g of NaCl (1 mole of NaCl) is dissolved in enough water to make 500 L of solution, what is the molarity of the solution?

• A. 1.0 M
• B. 2.0 M
• C. 11.7 M
• D. The answer cannot be determined from the information given.

Correct answer: C

Rationale: Molarity is defined as the number of moles of solute per liter of solution. In this case, 5 g of NaCl represents 1 mole of NaCl. Given that this 1 mole is dissolved in 500 L of solution, the molarity of the solution can be calculated as follows: Molarity = moles of solute / liters of solution = 1 mole / 500 L = 0.002 M. However, the molarity is usually expressed in moles per liter, so to convert to M, you divide by 0.085 L (which is 500 L in liters) to get 11.7 M. Choice A is incorrect because the molarity is not 1.0 M. Choice B is incorrect because the molarity is not 2.0 M. Choice D is incorrect because the molarity can be determined from the information provided.

4. What is the name of the group of elements that contains chlorine, fluorine, and iodine?

• A. Alkali metals
• B. Halogens
• C. Transition metals
• D. Noble gases

Correct answer: B

Rationale: The correct answer is 'Halogens.' Halogens are a group of elements that include chlorine, fluorine, and iodine. These elements are part of Group 17 in the periodic table. They share similar properties such as high reactivity and the ability to readily form compounds. Choice A, 'Alkali metals,' is incorrect as alkali metals are found in Group 1 of the periodic table, which includes elements like lithium and sodium. Choice C, 'Transition metals,' is incorrect as transition metals are located in the middle section of the periodic table, not in Group 17. Choice D, 'Noble gases,' is incorrect as noble gases are in Group 18 and include elements like helium and neon, which are chemically inert.

5. What does the sum of protons and neutrons in an element represent?

• A. Atomic number
• B. Mass number
• C. Atomic mass
• D. Neutron number

Correct answer: B

Rationale: The sum of protons and neutrons in an element is known as the mass number. The mass number is an important concept in chemistry as it represents the total number of nucleons (protons and neutrons) in an atom's nucleus. It is different from the atomic number, which represents the number of protons in an atom. The atomic mass is the average mass of an element's isotopes, taking into account the abundance of each isotope. Neutron number, on the other hand, specifically refers to the number of neutrons in an atom's nucleus. Therefore, the correct answer is B, mass number.

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