According to charle's Law, which of the following is constant?

Appeared in: DSSSB -28 August 2019 (Shift-2)

Explanation

Charles's Law describes the relationship between the volume and temperature of a gas at constant pressure.
It states that volume (V) is directly proportional to the absolute temperature (T).
This direct proportionality is expressed mathematically as V/T = k, where k is a constant.

Option A: The product of pressure and temperature (PT) is not held constant in any of the simple gas laws.
Option B: The product of pressure and volume (PV) is constant according to Boyle's Law, not Charles's Law.
Option D: The ratio of pressure to temperature (P/T) is constant according to Gay-Lussac's Law, not Charles's Law.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Ideal Gas Laws (Charles's Law) as background academic context rather than a clinical decision trigger.
Understanding gas laws is fundamental in respiratory care for managing mechanical ventilators. The temperature of inspired gases can affect the volume delivered to the patient's lungs.
What if? If a cylinder of medical oxygen is moved from a cold outdoor area to a warm indoor room, its internal pressure will increase (Gay-Lussac's Law), which is a critical safety consideration for storage and handling.

How to Approach the Question

First, identify the key concept in the question, which is 'Charles's Law'.
Recall the definition of Charles's Law: At constant pressure, the volume of a gas is directly proportional to its absolute temperature.
Translate this definition into a mathematical relationship: V ∝ T.
Rearrange the proportionality into an equation with a constant: V/T = constant.
Compare this equation to the given options and select the one that matches.

Concept Tested & Keywords

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Practise the full DSSSB -28 August 2019 (Shift-2)

Attempt every question from this paper in a timed mock, then review the full solution for each one.