Final answer:
To calculate the number of moles in 3.7 * 10^25 formula units of potassium chloride, use the molar ratio of 6.022 x 10^23 formula units per mole.Therefore, the correct answer is 6.1 moles (option c).
Step-by-step explanation:
To calculate the number of moles in 3.7 * 10^25 formula units of potassium chloride, we need to know the molar ratio between formula units and moles for potassium chloride. The molar ratio is 6.022 x 10^23 formula units per mole. We can use this ratio to convert from formula units to moles.
3.7 * 10^25 formula units * (1 mole / 6.022 x 10^23 formula units) = 6.1 moles
Therefore, the correct answer is 6.1 moles (option c).