MCAT (Chemical and Physical Foundations) 4

Question 1

Light travels from glass (n = 1.5) into water (n = 1.33). What is the critical angle for total internal reflection?

Accepted Answer

62.5°

Answer

sin(θc) = n₂/n₁ = 1.33/1.5 = 0.887; θc = arcsin(0.887) ≈ 62.5°.

Question 2

Which of the following has the highest electron affinity?

Accepted Answer

Cl

Answer

Chlorine has the highest electron affinity among these elements because gaining one electron completes its valence shell with minimal electron-electron repulsion.

Question 3

A 0.5 mol sample of an ideal gas occupies 11.2 L at STP. If the temperature is doubled at constant pressure, what is the new volume?

Accepted Answer

22.4 L

Answer

By Charles's Law, V₁/T₁ = V₂/T₂; doubling T at constant P doubles V: 11.2 × 2 = 22.4 L.

Question 4

In a second-order reaction, when the initial concentration of reactant is doubled, what happens to the half-life?

Accepted Answer

It is halved

Answer

For a second-order reaction, t½ = 1/(k[A]₀); doubling [A]₀ halves the half-life.

Question 5

Which property of sound waves increases when the medium's temperature rises?

Accepted Answer

Speed

Answer

Sound speed in a gas increases with temperature because molecules move faster, transmitting vibrations more quickly.

MCAT - Medical College Admission Test Practice Test

MCAT - Medical College Admission Test Practice Test

MCAT (Chemical and Physical Foundations) 4