Unit 4: Chemistry Fundamentals

Answer: D — Hydrogen bonding between polar molecules is the strongest type of intermolecular force and would result in the highest boiling point. London dispersion forces (A) are the weakest type of intermolecular force and would not result in a high boiling point. Dipole-dipole forces (B) are stronger than London dispersion forces but weaker than hydrogen bonding. Hydrogen bonding between nonpolar molecules (C) is not possible, as hydrogen bonding requires a polar molecule with a hydrogen atom bonded to a highly electronegative atom.

Answer: B — The correct answer, B, is correct because as you move from left to right across a period in the periodic table, the number of protons in the nucleus increases. This increase in nuclear charge leads to a stronger attraction to the electrons, resulting in a smaller atomic radius. Option A is incorrect because an increase in nuclear charge would lead to a stronger attraction to the electrons, not a decrease. Option C is incorrect because the number of electron shells does not increase as you move from left to right across a period. Option D is incorrect because the number of electron shells does not decrease as you move from left to right across a period.

Answer: C — The correct answer is C because the pH level of the water is the variable being manipulated and tested in the experiment. The other options are incorrect because the type of plant, amount of water, and type of soil are all controlled variables that remain the same in each experiment. This question requires the ability to identify and describe variables, which is a key skill in the scientific method.

Answer: B — The correct answer is B) 1 mole, because the mass of the sample (70.9 g) is equal to the molar mass of chlorine (70.9 g/mol), so the number of moles is 1. The other options are incorrect because they do not accurately reflect the relationship between the mass of the sample and the molar mass of chlorine. Option A is incorrect because 0.5 moles would have a mass of 35.45 g, option C is incorrect because 2 moles would have a mass of 141.8 g, and option D is incorrect because 3 moles would have a mass of 212.7 g.

Answer: C — The correct answer is C) Ionic bond. Ionic bonds are typically found in compounds with high melting points, are brittle, and do not conduct electricity. Hydrogen bonds (A) are typically found in compounds with lower melting points and are not as brittle. Metallic bonds (B) are found in metals, which are typically good conductors of electricity. Covalent bonds (D) can be found in a wide range of compounds, but are not typically associated with the properties described. Therefore, ionic bonds are the most likely type of bond present in the compound.