Nursing Elites

1. Which two elements are most alike in reactivity?

• A. He and H
• B. K and Ar
• C. Cl and P
• D. Ba and Mg

Correct answer: C

Rationale: Chlorine (Cl) and Phosphorus (P) are most alike in reactivity among the given pairs. Both elements are nonmetals and belong to Group 7 (halogens) and Group 15 (nitrogen group), respectively. They have similar electronic configurations and can form compounds by gaining or sharing electrons. Chlorine is highly reactive and can easily form ionic compounds, while phosphorus also shows a range of reactivity in its compounds. Choice A (He and H) is incorrect because helium (He) is a noble gas and hydrogen (H) is a nonmetal, so they are not similar in reactivity. Choice B (K and Ar) is incorrect as potassium (K) is a metal and argon (Ar) is a noble gas, having different reactivities. Choice D (Ba and Mg) is incorrect because barium (Ba) and magnesium (Mg) are both metals, but their reactivities differ due to their positions in the periodic table.

2. If oxygen is in a compound, what would its oxidation number be?

• A. 2
• B. -2
• C. 0
• D. -1

Correct answer: B

Rationale: Oxygen typically has an oxidation number of -2 in compounds because it tends to gain electrons. This is due to its high electronegativity, which leads to oxygen attracting electrons towards itself in a chemical bond. Choice A (2) is incorrect because oxygen doesn't have a +2 oxidation number in compounds. Choice C (0) is incorrect as oxygen rarely has an oxidation number of 0 in compounds. Choice D (-1) is incorrect as oxygen's oxidation number in compounds is typically -2, not -1.

3. Which element is considered a noble gas?

• A. Oxygen
• B. Neon
• C. Hydrogen
• D. Argon

Correct answer: B

Rationale: The correct answer is 'Neon.' Noble gases are a group of elements with very low reactivity. Neon is one of these elements, known for its stable and unreactive nature. Oxygen, hydrogen, and argon do not belong to the noble gas group. Oxygen is a reactive non-metal, hydrogen is a non-metal and the first element in the periodic table, and argon is a noble gas like neon but not the correct answer in this case.

4. What are the columns of the periodic table called?

• A. Periods
• B. Families
• C. Groups
• D. Rows

Correct answer: C

Rationale: In the periodic table, columns are referred to as groups, not periods, families, or rows. These groups share similar chemical properties due to the arrangement of elements within each group, which is based on the number of valence electrons. The vertical columns help classify elements with similar characteristics. Periods refer to the rows of the periodic table, while families or groups are the vertical columns.

5. What does the mass of one mole of a substance represent?

• A. Atomic mass
• B. Mass number
• C. Molecular weight
• D. Molar mass

Correct answer: D

Rationale: The mass of one mole of a substance is represented by its molar mass. Molar mass is the mass of one mole of a substance and is expressed in grams per mole. It is calculated by summing the atomic masses of all atoms in a molecule. Therefore, the correct answer is D - 'Molar mass'. Choice A, 'Atomic mass', refers to the average mass of an atom of an element. Choice B, 'Mass number', is the total number of protons and neutrons in an atom's nucleus. Choice C, 'Molecular weight', is the average mass of a molecule relative to 1/12 of the mass of an atom of carbon-12.

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