JEE Main 2025 · 29 January · morning · Numerical answer · +4 / −1
A container of fixed volume contains a gas at 27°C. To double the pressure of the gas, the temperature of gas should be raised to _____ °C.
Answer and solution
Answer 327
Solution
Physics sir · 3 steps
Fixed volume means pressure follows absolute temperature, so convert to kelvin before you double anything.
- Fixed volume. From PV = nRT with V and n constant, P ∝ T. Here T must be the absolute temperature in kelvin.
P₂/P₁ = T₂/T₁
- Put in numbers. T₁ = 27 + 273 = 300 K. Doubling the pressure needs T₂ = 2 × 300 = 600 K.
- So. Back to Celsius: 600 - 273 = 327 °C. The answer is 327.
The common slip: 54. Doubling the Celsius temperature directly gives 54 °C, which is wrong because pressure is proportional to kelvin temperature, not Celsius.
The idea to keep. Gas laws only work in kelvin. Convert to kelvin first, do the ratio, then convert back to °C at the end if the question asks for it.
Answer from the NTA final answer key. Solution by PrepWiser.