Calculate the mass, in grams, of 912 atoms of iron, Fe (1 mol of Fe
has a mass of 55.85 g).

8.45 × 10⁻²⁰ g

Explanation:

Step 1: Given data

Step 2: Calculate the mass, in grams, of 1 atom of Fe

We will use Avogadro's number: there are 6.02 × 10²³ atoms of Fe in 1 mole of Fe.

55.85 g/mol × 1 mol/6.02 × 10²³ atom = 9.27 × 10⁻²³ g/atom

Step 3: Calculate the mass corresponding to 912 atoms

9.27 × 10⁻²³ g/atom × 912 atom = 8.45 × 10⁻²⁰ g

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.