Nursing Elites

1. Which of the following elements is a halogen?

• A. Oxygen
• B. Fluorine
• C. Sodium
• D. Carbon

Correct answer: B

Rationale: The correct answer is 'Fluorine' (Choice B) as it is a halogen. Halogens are a group of elements that include fluorine, chlorine, bromine, iodine, and astatine. They are highly reactive nonmetals located in Group 17 of the periodic table. Oxygen (Choice A) is a nonmetal but not a halogen. Sodium (Choice C) is a metal, and Carbon (Choice D) is a nonmetal, neither of which belong to the halogen group.

2. What term refers to the average of the masses of each of its isotopes as they occur in nature?

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

Correct answer: C

Rationale: The correct answer is atomic mass. Atomic mass is the weighted average of the masses of an element's isotopes. It takes into account the abundance of each isotope in nature to provide a more accurate representation of the element's overall mass. Choice A, atomic number, represents the number of protons in an atom. Choice B, mass number, refers to the total number of protons and neutrons in an atom's nucleus. Choice D, neutron number, specifically focuses on the count of neutrons in an atom's nucleus. These choices do not directly relate to the average mass of isotopes as asked in the question.

3. Which of these intermolecular forces might represent attraction between atoms of a noble gas?

• A. Dipole-dipole interaction
• B. London dispersion force
• C. Keesom interaction
• D. Hydrogen bonding

Correct answer: B

Rationale: Noble gases are non-polar molecules without a permanent dipole moment. The only intermolecular force applicable to noble gases is the London dispersion force, also known as Van der Waals forces. This force is a temporary attractive force resulting from the formation of temporary dipoles in non-polar molecules. Dipole-dipole interactions, Keesom interactions, and hydrogen bonding involve significant dipoles or hydrogen atoms bonded to electronegative atoms, which do not apply to noble gases.

4. Which compound contains a polar covalent bond?

• A. O
• B. F
• C. Br
• D. H₂O

Correct answer: D

Rationale: The compound 'H₂O' (water) contains a polar covalent bond. In a water molecule, the oxygen atom is more electronegative than the hydrogen atoms. As a result, the electrons in the O-H bonds are unevenly shared, leading to a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms. This unequal sharing of electrons creates a polar covalent bond in water. Choices A, B, and C are incorrect because they represent individual elements, not compounds, and do not involve the concept of polar covalent bonds.

5. What is a balanced equation?

• A. A description where reactants and products are not equal
• B. An equation where the number of each type of atom is the same on both sides
• C. A chemical formula showing only reactants
• D. An equation without coefficients

Correct answer: B

Rationale: A balanced equation is one where the number of each type of atom is the same on both sides, fulfilling the law of conservation of mass. This principle ensures that the total number of atoms of each element is equal in both reactants and products, signifying that no atoms are created or destroyed, but rather rearranged. Choice A is incorrect because a balanced equation has equal numbers of atoms in the reactants and products. Choice C is incorrect as a balanced equation includes both reactants and products. Choice D is incorrect because coefficients are essential in balancing equations by adjusting the number of atoms present.

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