Final answer:
Using moles as an intermediary, we determined that 10.0 grams of oxygen contains more molecules than 50.0 grams of iodine because it converts to a greater number of moles.
Step-by-step explanation:
To determine which contains more molecules, 10.0 grams of oxygen (O₂) or 50.0 grams of iodine (I₂), we need to calculate the number of moles of each substance because the number of molecules is directly proportional to the amount in moles.
Step 1: Calculate the moles of O₂ using the molecular weight of O₂ (32.00 g/mol).
\[ \frac{10.0 \text{ g O₂}}{32.00 \text{ g/mol}} = 0.3125 \text{ mol O₂} \]
Step 2: Calculate the moles of I₂ using the molecular weight of I₂ (2 × 126.90 g/mol = 253.80 g/mol).
\[ \frac{50.0 \text{ g I₂}}{253.80 \text{ g/mol}} = 0.197 \text{ mol I₂} \]
Since 1 mole of any substance contains Avogadro's number of molecules (6.022 × 1023 molecules/mol), we can conclude that 10.0 grams of oxygen contains more molecules than 50.0 grams of iodine because 0.3125 mol of oxygen is more than 0.197 mol of iodine.