Calculate the concentration of vacancies in in fcc silver at 250oC given that the activation energyfor vacancy creation in silver is 79.5 kJ/mol. The units for your answer should be vacancies/cm3.

The concentration of vacancies in fcc silver is

Explanation:

Given is - silver (fcc lattice)

Temperature = 250°C = 523K

Activation energy for vacancy creation , =79.5 kJ/mol

Silver has a fcc crystal lattice structure with basis

Lattice parameter = 0.49nm = m

Now , let us calculate number of silver atoms"(lattice points)per

     = atoms/

Concentration of vacancies is given by the formula -

here,

Activation energy for vacancy creation

T = Temperature

R = constant =

Now , putting the given values in the formula -

      =

Hence , the answer is

b is the correct