Question

The average kinetic energy per molecule of helium gas at temperature T is E and the molar gas constant is R, then Avogadro’s number is

• A.
  
• B.
  
  
• C.
  
  
• D.
  
  

Answer 1

The correct option is D



Average kinetic energy per unit molecule $E=\frac{3}{2}kT\therefore k=\frac{2E}{3T}$
But Avogadro number $=N_A=\frac{R}{k}\frac{R}{\left(2E/3T\right)}\therefore N_A=\frac{3RT}{2E}$