JEE Main201910 Jan 2019Evening ShiftPhysicsKinetic Theory of GasesActual
2 kg of a monoatomic gas is at a pressure of 4 × 10 4 N m - 2 . The density of the gas is 8   kg m - 3 . What is the order of energy of the gas due to its thermal motion?
Options
- A10 5   J
- B10 6   J
- C10 4   J
- D10 3   J
Correct answer
C. 10 4   J
Step-by-step solution
Internal energy is the energy due to thermal motion. The internal energy of an ideal gas given by U = f 2 n R T (for n   moles ) U = f 2 P V = f 2 × P × M ρ (Since, f = 3   for a monoatomic gas.) U = 3 2 × 4 × 10 4 × 2 8 = 1.5 × 10 4 J So, the order of energy due to thermal motion is 10 4