Question

What mass of iodine contains the same number of atoms at 25.0 g of chlorine?

Answer 1

I assume that you mean Cl2 gas, and molecular (solid) I2. 25 g of chlorine would be 25/71 or 35.2% of a mole. (The molar mass of Cl is 35.5; double that for Cl2)

1 mole of I2 has a mass of
0.352*2*126.9 g = 89.34 g

Answer 2

89.52