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Question 1:

What is a covalent bond?

A) A bond formed between a metal and a nonmetal
B) A bond formed between two nonmetals
C) A bond formed between two metals
D) A bond formed between a metal and a metalloid

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Explanation: The correct answer is B) A bond formed between two nonmetals. A covalent bond is formed when two nonmetal atoms share one or more pairs of electrons. This sharing of electrons allows both atoms to achieve a more stable electron configuration.

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Question 2:

What is the maximum number of covalent bonds an atom of carbon can form?

A) 2
B) 3
C) 4
D) 5

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Explanation: The correct answer is C) 4. An atom of carbon has 4 valence electrons in its outermost energy level. To achieve a stable electron configuration, carbon can share these 4 electrons by forming covalent bonds with other atoms. Therefore, carbon can form a maximum of 4 covalent bonds.

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Question 3:

What is the shape of a molecule with a central atom and three surrounding atoms?

A) Linear
B) Trigonal planar
C) Tetrahedral
D) Octahedral

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Explanation: The correct answer is B) Trigonal planar. A molecule with a central atom and three surrounding atoms adopts a trigonal planar shape. The three surrounding atoms are arranged in a flat triangular geometry around the central atom.

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Question 4:

Which of the following pairs of elements would most likely form a covalent bond?

A) Sodium (Na) and Chlorine (Cl)
B) Oxygen (O) and Fluorine (F)
C) Potassium (K) and Sulfur (S)
D) Magnesium (Mg) and Oxygen (O)

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Explanation: The correct answer is B) Oxygen (O) and Fluorine (F). Oxygen and fluorine are both nonmetals and have a strong tendency to gain electrons to achieve a stable electron configuration. When they come together, they can share electrons and form a covalent bond to achieve stability.

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Question 5:

Which of the following substances does not exhibit covalent bonding?

A) Water (H2O)
B) Methane (CH4)
C) Sodium chloride (NaCl)
D) Carbon dioxide (CO2)

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Explanation: The correct answer is C) Sodium chloride (NaCl). Sodium chloride, also known as table salt, exhibits ionic bonding rather than covalent bonding. It is formed through the transfer of electrons between a metal (sodium) and a nonmetal (chlorine).