Gas Laws: Volume Inversely Proportional to Pressure, Directly to Temperature

Steps:

• Recall the combined gas law: V ∝ T/P (volume increases with temperature, decreases with pressure).
• For volume to decrease, temperature must decrease (lowers V) or pressure must increase (lowers V).
• Evaluate each option: both changes must reduce V.
• Identify the pair where T decreases and P increases.

Why C is correct:

• Per Charles's and Boyle's laws, decreasing T reduces V (V ∝ T), and increasing P reduces V (V ∝ 1/P).

Why the others are wrong:

• A: Increasing T increases V; decreasing P increases V—both expand gas.
• B: Decreasing T decreases V, but decreasing P increases V—opposing effects.
• D: Increasing T increases V; increasing P decreases V—opposing effects.

Final answer: C