NSAA NSAA Physics - Thermal Physics and Thermodynamics 3

Question 1

The root mean square (rms) speed of ideal gas molecules is proportional to:

Accepted Answer

Square root of temperature √T

Answer

From v_rms = √(3RT/M), the rms speed is proportional to √T, so doubling temperature increases rms speed by factor √2.

Question 2

Which equation correctly describes the ideal gas law, where n is moles and R is the universal gas constant?

Accepted Answer

PV = nRT

Answer

The ideal gas law PV = nRT combines Boyle's, Charles's, and Gay-Lussac's laws into one equation.

Question 3

The third law of thermodynamics states that:

Accepted Answer

The entropy of a perfect crystal approaches zero as temperature approaches absolute zero

Answer

The third law establishes an absolute entropy reference: S → 0 as T → 0 K for a perfect crystalline solid.

Question 4

Heat transfer by convection occurs primarily in which medium?

Accepted Answer

Fluids (liquids and gases)

Answer

Convection requires bulk movement of matter to carry thermal energy, which only occurs in fluids where molecules can flow.

Question 5

An ideal gas is compressed isothermally so that its volume halves. What happens to its pressure?

Accepted Answer

Pressure doubles

Answer

By Boyle's Law (P₁V₁ = P₂V₂ at constant T), halving the volume doubles the pressure.

NSAA - Natural Sciences Admissions Assessment Practice Test