MCAT (Chemical and Physical Foundations) 2

Question 1

A buffer solution contains 0.10 M acetic acid and 0.15 M sodium acetate (pKa = 4.76). What is the pH of this buffer?

Accepted Answer

4.94

Answer

Using Henderson-Hasselbalch: pH = 4.76 + log(0.15/0.10) = 4.76 + 0.18 = 4.94.

Question 2

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number (l)

Answer

The angular momentum quantum number (l) defines the shape of an orbital (s, p, d, f).

Question 3

A 70 kg person stands on a scale in an elevator accelerating upward at 2 m/s². What does the scale read? (g = 10 m/s²)

Accepted Answer

840 N

Answer

Apparent weight = m(g + a) = 70(10 + 2) = 840 N.

Question 4

Which of the following molecules has the highest boiling point?

Accepted Answer

NH3

Answer

NH3 has the highest boiling point due to hydrogen bonding between molecules, which requires more energy to overcome.

Question 5

An ideal gas undergoes an isothermal expansion. Which thermodynamic statement is correct?

Accepted Answer

ΔU = 0 and w < 0

Answer

In isothermal expansion of an ideal gas, ΔU = 0 (temperature constant), and the gas does positive work on surroundings (w < 0 in sign convention where w = work done on system).

MCAT - Medical College Admission Test Practice Test

MCAT - Medical College Admission Test Practice Test

MCAT (Chemical and Physical Foundations) 2