Final answer:
The mass in grams of 6.42 × 10¹⁵ molecules of I₂ is calculated by converting the number of molecules to moles using Avogadro's number, and then converting moles to grams using the molar mass of I₂. The correct mass is 270.46 grams, which does not match any of the provided options.
Step-by-step explanation:
To find the mass in grams of 6.42 × 10¹⁵ molecules of I₂, we first need to use Avogadro's number to find the number of moles, since one mole of any substance contains 6.022 × 10¹⁵ entities (atoms, molecules, etc.).
Step 1: Calculate the number of moles
(6.42 × 10¹⁵ molecules I₂) ÷ (6.022 × 10¹⁵ molecules/mol) = 1.066 moles of I₂
Next, we find the molar mass of I₂. The atomic mass of one iodine (I) atom is approximately 126.9 amu, so for I₂, the molar mass is 253.8 g/mol.
Step 2: Convert moles to grams
1.066 moles × 253.8 g/mol = 270.46 grams
Therefore, none of the options (a, b, c, d) precisely matches our calculation. It seems there might be a typo or an error in the provided options. The correct mass, based on our calculation, is 270.46 grams.