Final answer:
The mass of 6.55 × 10^25 molecules of Cl2 is calculated using conversion factors and proportional relationships, yielding a mass of 7694.6855 grams, which suggests the correct answer may be that more information is needed.
Step-by-step explanation:
The question is asking for the mass in grams of 6.55 × 1025 molecules of Cl2. To calculate this, we will need to use the provided conversion factors: 1 mole of Cl2 is equivalent to 70.90 g and 6.022 × 1023 molecules of Cl2 is equivalent to 1 mole of Cl2. By setting up a proportional relationship, we compare the number of molecules we have to Avogadro's number (6.022 × 1023 molecules/mol), and then use the molar mass to find the answer without explicitly calculating moles:
Molecules of Cl2 × (1 mol Cl2 / 6.022 × 1023 molecules of Cl2) × (70.90 g / 1 mol Cl2) = Mass in grams
Substituting the given number of molecules:
6.55 × 1025 × (1 mol Cl2 / 6.022 × 1023 molecules of Cl2) × (70.90 g / 1 mol Cl2) = Mass in grams
Upon simplifying, you find that the mass of Cl2 is 7694.6855 g, which is not one of the options given. Hence, the correct answer to the question might be (a) Need more information, considering there may be an error in the options provided.