HI was heated in the sealed tube at 400 degree Celsius still the equilibrium .HIHwas found to be 22% decomposed the equilibriumCONSTANT of the dissociation is

there r 2of eq. constant

K_c  & K_p  

           rxn       2HI -> H₂ +I₂

  moles initally   2        0     0

moles @eqlb.   2-2x    x      x    

                                K_c   =  x*x/{2-2x}^2 = (0.22)^2/4*(0.78)^2 = 0.19888

conc.(C)= P/RT  for gas phase rxn  

                                         RT *(x)= P_{H2 =} P_{I2   =} 0.19888        (same as   K_c bcz  power o RT cancel out  )