Which graph best represents the relationship between temperature and volume for a gas at constant pressure, as described by Charles' Law?

• A. A horizontal line, showing volume remaining constant as temperature increases
• B. A curve that approaches zero volume as temperature increases
• C. A straight line with a negative slope, showing volume decreasing as temperature increases
• D. A straight line with a positive slope, showing volume increasing linearly with temperature (in Kelvin)

Answer: (D)

Verified step by step guidance

1. Recall Charles' Law, which states that for a given amount of gas at constant pressure, the volume of the gas is directly proportional to its absolute temperature (in Kelvin). Mathematically, this is expressed as \(V \propto T\) or \(\frac{V}{T} = k\), where \(k\) is a constant.
2. Understand that because volume and temperature are directly proportional, if temperature increases, volume must also increase, and if temperature decreases, volume decreases accordingly.
3. Recognize that when plotting volume (\(V\)) on the y-axis and temperature (\(T\) in Kelvin) on the x-axis, the graph should be a straight line passing through the origin (or close to it if extrapolated), indicating a linear relationship with a positive slope.
4. Eliminate options that do not fit this direct proportionality: a horizontal line (volume constant), a curve approaching zero volume as temperature increases, or a line with a negative slope (volume decreasing with temperature) are inconsistent with Charles' Law.
5. Conclude that the correct graph is a straight line with a positive slope, showing volume increasing linearly with temperature in Kelvin, which visually represents the direct proportionality described by Charles' Law.