clc
//initialisation of variables
M= 0.001 //molar
M1= 0.002 //molar
M2= 0.004 //molar
n= 1 //moles
n1= 2 //moles
v= 0.509
//CALCULATIONS
Is= 0.5*(M*n^2+M1*n^2+M1*n1^2+M2*n^2)
r= 10^(-v*n^2*sqrt(Is))*M
r1= 10^(-v*n1^2*sqrt(Is))*M1
//RESULTS
printf (' ionic strength= %.3f ',Is)
printf (' \n activity of sodium = %.4f molar',r)
printf (' \n activity of barium = %.4f molar',r1)