In this question, we need to calculate the mass in grams of 5.67*10^24 molecules of CoCl2. The first thing we need to do is to find the number of moles that we have in this amount of molecules, in order to do so, we use the Avogadro's number, which is 6.02 * 10^23 molecules in 1 mol:
6.02*10^23 molecules = 1 mol
5.67*10^24 molecules = x moles
6.02*10^23x = 5.67*10^24
x = 5.67*10^24/6.02*10^23
x = 9.418 moles of CoCl2 in 5.67*10^24 molecules
Now that we have the number of moles, 9.418, we can calculate the mass, using the molar mass of CoCl2, 129.84 grams/mol:
129.84 grams = 1 mol
x grams = 9.418 moles
x = 9.418 * 129.84
x = 1,222.5 grams
The answer will be letter B, 1,222.5g
