Gay-Lussac's Law at Constant Volume

Steps:

• Identify the conditions: sealed syringe means constant volume and moles of gas.
• Recall the ideal gas law: PV = nRT, where P is pressure, V is volume, n is moles, R is constant, T is temperature.
• Rearrange for constant V and n: P ∝ T, so pressure changes directly with temperature.
• Conclude: increasing temperature raises pressure; decreasing it lowers pressure.

Why C is correct:

• Gay-Lussac's Law states that at constant volume, pressure is directly proportional to absolute temperature (P/T = constant).

Why the others are wrong:

• A: Decreasing temperature decreases pressure, not increases it.
• B: Increasing temperature changes pressure, it does not remain unchanged.
• D: Increasing temperature changes pressure, it does not remain unchanged.

Final answer: C