The initial volume of a gas at 300 K was 220 cm 3 Determine its temperature if the volume became 250 cm 3

Analyze the question: A gas changes volume from 220 cm³ to 250 cm³. The initial temperature is 300 K. We need the new temperature. The question doesn't mention pressure, so we assume it stays constant.

Concept: Charles's Law At constant pressure, the volume of a fixed mass of gas is directly proportional to its absolute temperature (in kelvin):

V₁/T₁ = V₂/T₂

Solution:

Given:

• V₁ = 220 cm³
• T₁ = 300 K
• V₂ = 250 cm³
• T₂ = ?

Rearrange for T₂:

T₂ = (V₂ × T₁) / V₁

T₂ = (250 × 300) / 220

T₂ = 75000 / 220

T₂ ≈ 340.9 K ≈ 341 K

Check: The volume increased, so the temperature should increase. 341 K is greater than 300 K, which makes sense. This also rules out A (183 K) and B (264 K), which are lower than 300 K. Option C (300 K) would mean no change in volume.

Tip: In Charles's Law questions, first decide the direction of change. If volume goes up, temperature goes up (at constant pressure), so you can quickly eliminate any option that is lower than the starting temperature. Also, always use kelvin, not °C. If the temperatures are given in °C, add 273 first.