The debye-hückel screening length in a 0.00100 molal solution of nacl in water at 298 k is:

Explanation:

Formula to calculate the Debye-Hückel screening length is as follows.

            ......... (1)

where,     = dielectric constt. of water = 78.5

                = permitivity of space =

                T = temperature = 298 K

  e = charge on electron =

  = Avogadro's number = ions/mol

       I = ionic activity = 0.001 molal

    = charge on the species = 1 (in case of both and )

Also,     I =

              =

              = 0.001 molal

Now, putting all the given values into equation (1) as follows.

                 =    

                 = m

                 =

Thus, we can conclude that Debye-Hückel screening length in given solution is .

i think its 100

i hope this !