Q: Which of the following is the correct formula for calculating the partial pressure of a gas in a mixture?

$$P_{gas} = P_{atm} \times \text{fraction of gas}$$

Question 1

Which equation correctly represents the Ideal Gas Law?

Accepted Answer

$$PV = nRT$$

Question 2

A patient inhales a breath of air at sea level (atmospheric pressure $$= 760$$ mmHg) with 21% oxygen. What is the partial pressure of oxygen in this breath?

Accepted Answer

$$160$$ mmHg

Question 3

According to Boyle's Law, if the volume of a gas in the lungs decreases from $$6 L to$$ $$3 L at $$constant temperature, what happens to the pressure?

Accepted Answer

It doubles

Question 4

Which law states that the total pressure of a mixture of gases is the sum of the partial pressures of each individual gas?

Accepted Answer

Dalton's Law

Question 5

If the resistance in a patient's airway doubles, what happens to the flow of air, assuming the pressure difference remains constant?

Accepted Answer

It is halved

Question 6

Which equation describes the relationship between pressure, force, and area in the context of atmospheric pressure?

Accepted Answer

$$P = \frac{F}{A}$$

Question 7

A patient is exposed to 100% humidity at $$37^\circC. $$How does the partial pressure of water vapor in their inspired air compare to dry air at $$25^\circC$$?

Accepted Answer

It is much higher

Question 8

Which of the following is NOT a determinant of the Ideal Gas Law?

Accepted Answer

Humidity

Question 9

According to Henry's Law, the amount of gas dissolved in a liquid is proportional to which factor?

Accepted Answer

The partial pressure of the gas

Question 10

Which lung volume cannot be measured directly by simple spirometry?

Accepted Answer

Residual Volume (RV)

Question 11

A patient’s functional residual capacity (FRC) is measured using the helium dilution technique. If the initial helium concentration is $$C_1$$ and the final concentration is $$C_2$$, which equation is used to calculate the unknown lung volume $$V_2$$?

Accepted Answer

$$V_2$$ = $$V_1$$ \left( \frac{$$C_1$$}{$$C_2$$} - 1 \right)$$

Question 12

Which of the following best explains why branching of airways increases total cross-sectional area and decreases air flow velocity?

Accepted Answer

Branching creates more parallel pathways for air to flow

Question 13

If a patient’s tidal volume (TV) is $$500 mL$$, expiratory reserve volume (ERV) is $$1200 mL$$, and residual volume (RV) is $$1300 mL$$, what is their functional residual capacity (FRC)?

Accepted Answer

$$2500 mL$$

Question 14

Which of the following statements about positive pressure ventilation is correct?

Accepted Answer

Air is pushed into the lungs by increasing pressure outside the airways

Question 15

Which factor will increase airway resistance the most?

Accepted Answer

Decreasing the radius of the airway

Question 16

A patient with Coal Worker's Pneumoconiosis (Black Lung Disease) is likely to have which change in their lung function?

Accepted Answer

Decreased cross-sectional airway area

Question 17

Which of the following is the correct formula for calculating the partial pressure of a gas in a mixture?

Accepted Answer

$$P_{gas} = P_{atm} 	imes 	ext{fraction of gas}$$

Question 18

Which of the following best describes the point in the breathing cycle represented by the functional residual capacity (FRC)?

Accepted Answer

The point where inward lung elastic recoil and chest wall outward expansion are balanced

Question 19

Which law explains why oxygen dissolves more readily in blood plasma at higher partial pressures?

Accepted Answer

Henry's Law

Module 3: Properties of Air, Gas Laws, and Functional Lung Volumes

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