AAMC MCAT Chemical and Physical Foundations 2 — Questions and Answers
Question 1: How does electronegativity difference affect bond polarity?
- Greater difference creates a more polar bond (Correct answer)
- Greater difference creates a nonpolar bond
- Electronegativity determines bond length only
- Electronegativity has no effect on bond type
Correct answer: Greater difference creates a more polar bond
A large electronegativity difference between bonded atoms creates a polar covalent or ionic bond, with electron density shifted toward the more electronegative atom.
Question 2: What does Beer-Lambert Law express mathematically?
- A = εlc (absorbance = molar absorptivity × path length × concentration) (Correct answer)
- A = hf (absorbance proportional to frequency)
- T = 1 − A (transmittance equals 1 minus absorbance)
- A = kT (absorbance proportional to temperature)
Correct answer: A = εlc (absorbance = molar absorptivity × path length × concentration)
Beer-Lambert Law (A = εlc) states that absorbance equals the product of molar absorptivity, path length, and concentration.
Question 3: Which intermolecular force explains water's unusually high boiling point?
- Hydrogen bonding (Correct answer)
- London dispersion forces
- Dipole-dipole interactions
- Ion-dipole interactions
Correct answer: Hydrogen bonding
Water forms extensive hydrogen bonds between electronegative oxygen and hydrogen atoms, dramatically raising the boiling point compared to similar-sized molecules.
Question 4: How does a catalyst affect activation energy and equilibrium?
- Lowers activation energy without shifting equilibrium (Correct answer)
- Lowers activation energy and shifts equilibrium toward products
- Raises activation energy for the reverse reaction
- Shifts equilibrium without affecting activation energy
Correct answer: Lowers activation energy without shifting equilibrium
A catalyst provides an alternative lower-energy pathway, speeding both forward and reverse reactions equally, leaving the equilibrium constant unchanged.
Question 5: What is Ohm's Law?
- V = IR (Correct answer)
- P = IV
- V = P/I
- R = V + I
Correct answer: V = IR
Ohm's Law (V = IR) states the voltage across a resistor equals the product of current flowing through it and its resistance.
Question 6: Which law states total gas pressure equals the sum of component partial pressures?
- Dalton's Law of Partial Pressures (Correct answer)
- Henry's Law
- Graham's Law
- Raoult's Law
Correct answer: Dalton's Law of Partial Pressures
Dalton's Law states each gas in a mixture exerts pressure independently, and total pressure is the sum of all partial pressures.
AAMC MCAT Chemical and Physical Foundations 2
How does electronegativity difference affect bond polarity?