Question

select the correct answer.
what do a mole of magnesium (mg) and a mole of iron (fe) have in common?
a. their number of atoms
b. their number of molecules
c. their number of electrons
d. their number of protons

Explanation:

Step1: Recall Avogadro's number

Avogadro's number ($N_A = 6.022\times10^{23}\text{ mol}^{-1}$) gives the number of entities (atoms, molecules etc.) in one mole.

Step2: Analyze for atoms

For any element in atomic form, 1 mole of that element contains $6.022\times 10^{23}$ atoms. So, 1 mole of Mg and 1 mole of Fe both contain $6.022\times 10^{23}$ atoms.

Step3: Analyze other options

• Option B: Mg and Fe are metals (not composed of molecules).
• Option C: Mg has 12 electrons per atom, Fe has 26 electrons per atom.
• Option D: Mg has 12 protons per atom, Fe has 26 protons per atom.

Answer:

A. their number of atoms