12. In a cylinder, a sample of an ideal gas undergoes an adiabatic process from the state (Pi,Vi) to (Pf,Vf) where P is the pressure and V is the volume. The sample-1 is a monatomic gas, and the sample-2 is a diatomic gas. The work done on the gas is W1 for sample-1 and W2 for sample-2. What is the value of the ratio W1/W2? (A) 1 (B) 5/2 (C) 3/5 (D) 2/3

10. The number of collisions a molecule makes per second is called collision frequency. At one atmosphere and 0 °C, estimate the collision frequency of air molecules. [The diameter of an air molecule under one atmosphere and 0 °C is approximately 3×10⁻¹⁰ (m), the average molecular speed is approximately 460 (m/s), and the molecular number density is approximately 2.7×10²⁵ molecules/m³]. (A) 3.5×10⁵ (collisions/s) (B) 3.5×10⁷ (collisions/s) (C) 3.5×10⁹ (collisions/s) (D) 3.5×10¹¹ (collisions/s)

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