Here's how to calculate the molecular mass of iodine pentafluoride (IF₅):

* Find the atomic masses:

* Iodine (I): 126.90 g/mol

* Fluorine (F): 18.998 g/mol

* Multiply the atomic mass of each element by its subscript in the formula:

* Iodine (I): 1 x 126.90 g/mol = 126.90 g/mol

* Fluorine (F): 5 x 18.998 g/mol = 94.99 g/mol

* Add the results together: 126.90 g/mol + 94.99 g/mol = 221.89 g/mol

Therefore, the molecular mass of iodine pentafluoride (IF₅) is 221.89 g/mol.