Under which conditions of pressure (p) and temperature (T) would the volume of an inflated ballon increase? When

Analyze the question: We want the conditions of pressure (P) and temperature (T) that make the volume of a fixed amount of gas in a balloon increase.

Concept (Gas Laws):

• Boyle's Law: At constant T, V ∝ 1/P. Lowering the pressure increases the volume.
• Charles's Law: At constant P, V ∝ T (in kelvin). Raising the temperature increases the volume.

Combined gas law:

So V is directly proportional to T and inversely proportional to P.

Step-by-step check of the options:

• A. P and T both increased: Higher T increases V, but higher P decreases V. The effects oppose each other, so the result is uncertain. ✗
• B. P and T both decreased: Lower P increases V, but lower T decreases V. Again the effects oppose, so the result is uncertain. ✗
• C. T increased, P decreased: Higher T increases V and lower P increases V. Both effects work together, so V definitely increases. ✓
• D. T decreased, P increased: Both effects decrease V. ✗

Answer: The volume definitely increases when temperature is raised and pressure is lowered, which is option C.

Exam tip: Remember "T goes with V, P goes against V." For V to rise with certainty, the two changes must push the same way: T up and P down (or the reverse for a decrease in V). When both factors point in the same direction, that is usually the intended answer. Also remember to convert °C to kelvin (K = °C + 273) in calculations.