Unit 2: Chemical Bonding

Answer: A — A double bond consists of one sigma bond and one pi bond, which matches the description given. A single bond (B) would only have one sigma bond, a triple bond (C) would have one sigma and two pi bonds, and a hydrogen bond (D) is a type of intermolecular force, not a type of covalent bond.

Answer: A — The correct answer is A because when two identical nonmetals share a pair of electrons, the bond is nonpolar covalent due to the equal sharing of electrons and the identical electronegativities of the atoms. Option B is incorrect because there is no difference in electronegativity between the identical atoms, so the bond cannot be polar covalent. Option C is incorrect because ionic bonds are formed between a metal and a nonmetal, not between two nonmetals. Option D is incorrect because covalent bonds can be formed between two nonmetals.

Answer: A — Correct answer D is accurate because the polar bonds between carbon and oxygen do indeed cancel each other out due to the molecule's linear shape. This results in a nonpolar molecule overall. Option A is incorrect because the polar bonds do not result in a polar molecule due to the symmetry. Option B is incorrect because the bonds between carbon and oxygen are polar, not nonpolar. Option C is incorrect because the shape of the molecule does have an effect on its polarity, as seen in the case of CO2.

Answer: D — The correct answer is A because the molecule has a bent shape and is composed of two different elements with different electronegativities. This results in an asymmetrical distribution of electron density, making the molecule polar. Option B is incorrect because the bent shape and difference in electronegativity make the molecule polar, not nonpolar. Option C is incorrect because the molecule is covalent, not ionic. Option D is incorrect because the molecule's polarity is due to its bent shape and the difference in electronegativity, not its linearity.

Answer: A — Correct answer A is true because chemical bonds are formed when atoms share or exchange electrons to achieve a more stable electronic configuration, often resulting in a full outer energy level. Incorrect answer B is wrong because proximity alone does not guarantee bond formation; electron configuration plays a crucial role. Incorrect answer C is wrong because the number of protons (atomic number) determines the element, not bond formation. Incorrect answer D is wrong because the number of neutrons (which determines the isotope) does not directly influence chemical bonding.