N-factor of a salt is the total positive charge or total negative charge. Let us find the total positive charge on potash alum. Potash alum has 2 potassium ions and 2 aluminium ions resulting in a total of 2*1+2*3=8 positive charge.

Therefore, the n-factor of potash alum is 8.

K2SO4.Al2(SO4)3.24.H2O

atomic mass of potassium, K = 39g/mol
atomic mass of sulphur, S = 32g/mol
​atomic mass of aluminium, Al = 27g/mol
atomic mass of oxygen, O = 16g/mol
​atomic mass of hydrogen, H = 1g/mol
​ 
Now molecular mass of  K2SO4.Al2(SO4)3.24.H2O​ = 2×(atomic mass of K + atomic mass of Al) + 4 × (molecular mass of SO4) + 24×( molecular mass of H2O)

molecular mass of  K2SO4.Al2(SO4)3.24.H2O​ = 2×(39+27) + 4× 96 + 24 × 18 = 948g/mol 

now calculate

948

Calculate sulphur