D425 Introduction to Chemistry - Set 1 - Part 3

Correct Answer: Polar molecules with hydrogen

Option b is correct because hydrogen bonding requires hydrogen attached to highly electronegative atoms like nitrogen, oxygen, fluorine.
Option a is incorrect because hydrogen bonding has specific requirements, not occurring between any arbitrary molecular combinations possible.
Option c is incorrect because nonpolar molecules lack the polarity and electronegative atoms necessary for hydrogen bonding.
Option d is incorrect because noble gases are monatomic and unreactive, unable to form hydrogen bonds or molecules.

Correct Answer: Inverse mass relationship

Option b is correct because molecular speed is inversely related to square root of molar mass at constant temperature.
Option a is incorrect because gas diffusion rates depend on molecular mass and kinetic energy, not color or appearance.
Option c is incorrect because heavier molecules move slower, not faster, showing inverse rather than direct mass relationship.
Option d is incorrect because temperature strongly affects molecular speeds; Graham's law applies at constant temperature conditions.

Correct Answer: Electrons delocalized

Option b is correct because resonance indicates electrons are spread over multiple positions rather than fixed locations.
Option a is incorrect because resonance specifically shows electrons aren't fixed but distributed among multiple possible arrangements.
Option c is incorrect because electrons are conserved in resonance structures; they're redistributed, not lost from molecules.
Option d is incorrect because electron number remains constant in resonance; only their distribution pattern is depicted differently.

Correct Answer: Mole fraction

Option b is correct because each gas's partial pressure is proportional to its mole fraction in the mixture.
Option a is incorrect because gas color has no relationship to pressure contribution in mixtures of multiple gases.
Option c is incorrect because pressure contributions depend on amount and properties, not arbitrary alphabetical naming conventions.
Option d is incorrect because historical discovery dates don't influence physical behavior or pressure contributions of gases.

Correct Answer: Increases measurably

Option b is correct because exothermic reactions release heat to surroundings, raising water temperature in the calorimeter.
Option a is incorrect because heat release from reactions warms surroundings; only endothermic reactions cool the water.
Option c is incorrect because heat transfer from reaction must change water temperature for calorimetric measurement to work.
Option d is incorrect because temperature changes systematically based on heat flow, not randomly fluctuating without pattern.

Correct Answer: Angular momentum number

Option b is correct because angular momentum quantum number determines orbital shape, with different values giving different geometries.
Option a is incorrect because principal quantum number determines size and energy but not the three-dimensional orbital shape.
Option c is incorrect because mass number counts protons plus neutrons, unrelated to electron orbital shapes or configurations.
Option d is incorrect because atomic number determines element identity and electron count, not individual orbital shapes.

Correct Answer: Unbalanced forces

Option b is correct because surface molecules experience unbalanced intermolecular forces, creating inward pull and surface tension.
Option a is incorrect because surface molecules are actually more ordered due to asymmetric forces, not randomly arranged.
Option c is incorrect because surface molecules have unequal force distribution unlike interior molecules surrounded by neighbors.
Option d is incorrect because surface tension results from intermolecular forces, not gravitational effects which are negligible.

Correct Answer: Relative affinities

Option b is correct because components with different affinities for mobile versus stationary phase travel different distances.
Option a is incorrect because mass alone doesn't determine travel distance; polarity and solubility are more important factors.
Option c is incorrect because separation depends on physical and chemical properties, not naming conventions or alphabetical order.
Option d is incorrect because historical discovery has no bearing on physical separation in chromatographic techniques or processes.

Correct Answer: Coordinate covalent

Option b is correct because ligands donate electron pairs to empty metal orbitals, forming coordinate covalent bonds.
Option a is incorrect because coordination compounds involve electron sharing through donation, not complete electron transfer to ions.
Option c is incorrect because metallic bonding occurs between metal atoms in bulk metals, not metal-ligand interactions.
Option d is incorrect because hydrogen bonding is an intermolecular force, not the primary metal-ligand bonding in complexes.

Correct Answer: Slowest step

Option b is correct because the slowest step acts as bottleneck, limiting overall reaction rate regardless of other steps.
Option a is incorrect because fast steps can't speed up overall rate if limited by a slower step in mechanism.
Option c is incorrect because first step only determines rate if it's also the slowest; position doesn't guarantee rate determination.
Option d is incorrect because last step only determines rate if it's slowest; sequential position doesn't determine rate importance.