MCAT TEST 16 (PRINCETON REVIEW TEST 1)
1. Mercury has a greater density than water, so what can we say about the
buoyant force and the force of surface tension?
Answer The buoyant force and surface tension are both greater in Mercury
2. What explains why a water droplet forms a roughly spherical shape if not
acted upon by external forces?
Answer A sphere minimizes the surface area of the shape for a given volume, which yields the lowest-
energy state for the molecules.
3. Units of surface tension coefficient
Answer
4. What would happen if an aluminum coin (ρ = 2700 kg/m3, L = 1 cm, V = 1 ×
10-8 m3) were gently placed on the surface of water?
Answer -The force of surface tension by itself would be suflcient to make the coin float.
-The maximum buoyant force for the coin is given by Fb = ρfVsubg, which for the given situation is Fb = (1000)(10-8)(10)
= 10-4 N. The weight of the coin is w = mg = ρcoinVg = (2700)(10-8)(10) = 2.7 × 10-4 N. The weight is greater than
,the buoyant force, so eliminate choice A
the buoyant force alone is not good enough. The maximum force of surface tension is Fst,y = γL (twice, because the
passage says that there are two of them). This comes out to Ftotal surface tension = (2)(0.07)(0.01) = 1.4 × 10-3 N.
That's greater than the weight, so the surface tension alone can balance the weight and allow the coin to float.
5. What explains why F2 is higher than Cl2 in the reactivity series? (what makes
F2 more reactive than Cl2)
Answer -F2 has a more negative Δ(SE)° than Cl2
-if the Δ(SE)° is more negative for F2, the overall ΔG° is more negative indicating it is more energetically favorable to
add an electron to F2 compared to Cl2.
6. What best explains the observed difference in electron affinity between chlo-
rine and fluorine?Answer Fluorine has a smaller atomic volume than chlorine, resulting in stronger repulsive
forces between the existing electrons and the electron being added
The smaller atomic volume leads to greater repulsive forces between the existing electrons and the electron being
added
7. A medium with index of refraction n is surrounded by air. The critical angle
,inside of the medium is then determined. The medium is then submerged in
a fluid with index of refraction nfluid. If 1 < nfluid < n how is the critical angle
affected?
Answer -It is measured inside of the medium and is greater than its previous value
-Total internal reflection can only happen when the incident medium has a greater index of refraction than the
surrounding medium. Since the original medium has a greater index of refraction than the fluid, it must still be the
incident medium.
, -Snell's law of refraction states that n1sinθ1 = n2sinθ2. For total internal reflection, θ1 = θcritical and θ2 = 90°, which
means that n1sinθcritical = n2. The index of refraction of air (n2 in this case) is 1, so immersing the medium in fluid has
caused n2 to increase. Since n1 remains constant, the equation tells us that sinθcritical, and therefore θcritical itself,
must increase.
8. The more negative the H0 of a superacid is means what?
Answer The more negative, the stronger the acid
9. What are the three major ways in which antibiotics interact with bacteria?
Answer -
-Membrane protein solubilization
-Leakage of cytosolic content
-Detergent fro the cell membrane
10. If a substrate has a positive charge on it, what kind of amino acid would most
likely be in the active site?
Answer -One with a positive charge like aspartic or glutamic acid- positive charge means negatively
acidic amino acids and vice versa
1. Mercury has a greater density than water, so what can we say about the
buoyant force and the force of surface tension?
Answer The buoyant force and surface tension are both greater in Mercury
2. What explains why a water droplet forms a roughly spherical shape if not
acted upon by external forces?
Answer A sphere minimizes the surface area of the shape for a given volume, which yields the lowest-
energy state for the molecules.
3. Units of surface tension coefficient
Answer
4. What would happen if an aluminum coin (ρ = 2700 kg/m3, L = 1 cm, V = 1 ×
10-8 m3) were gently placed on the surface of water?
Answer -The force of surface tension by itself would be suflcient to make the coin float.
-The maximum buoyant force for the coin is given by Fb = ρfVsubg, which for the given situation is Fb = (1000)(10-8)(10)
= 10-4 N. The weight of the coin is w = mg = ρcoinVg = (2700)(10-8)(10) = 2.7 × 10-4 N. The weight is greater than
,the buoyant force, so eliminate choice A
the buoyant force alone is not good enough. The maximum force of surface tension is Fst,y = γL (twice, because the
passage says that there are two of them). This comes out to Ftotal surface tension = (2)(0.07)(0.01) = 1.4 × 10-3 N.
That's greater than the weight, so the surface tension alone can balance the weight and allow the coin to float.
5. What explains why F2 is higher than Cl2 in the reactivity series? (what makes
F2 more reactive than Cl2)
Answer -F2 has a more negative Δ(SE)° than Cl2
-if the Δ(SE)° is more negative for F2, the overall ΔG° is more negative indicating it is more energetically favorable to
add an electron to F2 compared to Cl2.
6. What best explains the observed difference in electron affinity between chlo-
rine and fluorine?Answer Fluorine has a smaller atomic volume than chlorine, resulting in stronger repulsive
forces between the existing electrons and the electron being added
The smaller atomic volume leads to greater repulsive forces between the existing electrons and the electron being
added
7. A medium with index of refraction n is surrounded by air. The critical angle
,inside of the medium is then determined. The medium is then submerged in
a fluid with index of refraction nfluid. If 1 < nfluid < n how is the critical angle
affected?
Answer -It is measured inside of the medium and is greater than its previous value
-Total internal reflection can only happen when the incident medium has a greater index of refraction than the
surrounding medium. Since the original medium has a greater index of refraction than the fluid, it must still be the
incident medium.
, -Snell's law of refraction states that n1sinθ1 = n2sinθ2. For total internal reflection, θ1 = θcritical and θ2 = 90°, which
means that n1sinθcritical = n2. The index of refraction of air (n2 in this case) is 1, so immersing the medium in fluid has
caused n2 to increase. Since n1 remains constant, the equation tells us that sinθcritical, and therefore θcritical itself,
must increase.
8. The more negative the H0 of a superacid is means what?
Answer The more negative, the stronger the acid
9. What are the three major ways in which antibiotics interact with bacteria?
Answer -
-Membrane protein solubilization
-Leakage of cytosolic content
-Detergent fro the cell membrane
10. If a substrate has a positive charge on it, what kind of amino acid would most
likely be in the active site?
Answer -One with a positive charge like aspartic or glutamic acid- positive charge means negatively
acidic amino acids and vice versa
