JEE Main202229 Jun 2022Morning ShiftPhysicsThermal Properties of MatterActual
A cylinder of fixed capacity of 44 . 8 litres contains helium gas at standard temperature and pressure. The amount of heat needed to raise the temperature of gas in the cylinder by 20 . 0 ° C will be (Given gas constant R = 8 . 3 J K - 1 mol - 1 )
Options
- A249   J
- B415   J
- C498   J
- D830   J
Correct answer
C. 498   J
Step-by-step solution
At STP volume occupied by one mole of a gas is 22 . 4   L . Therefore, number of moles are, n = 44 . 8 22 . 4 = 2   mol . The process is isochoric process as the volume of the cylinder remains fixed and helium is a monatomic gas. Therefore, amount of heat needed will be, Q = n Cv Δ T = 2 3 2 R 20 = 3 × 8 . 3 × 20 = 498   J