Question

Question #19e39

Answer 1

`= 1.202*10^24Ca` Atoms

Explanation:

We are doing a grams to moles to atoms conversion.

You will need Avogadro's Constant and the amount of grams per mole of Calcium from whichever periodic table you happen to have.

I used Ptable.

`80.0gCa*(1molCa)/(40.078g Ca)*(6.022*10^23 Ca)/(1molCa)` Atoms

You can always double check to make the proper units are left in numerator of the last conversion factor.

`= 1.202*10^24Ca` Atoms

For proper significant figures, if you were given the value (80g) for Calcium, there is only one significant figure in that number.
Thus, your answer would only be good to one significant figure:

`=10^24Ca` Atoms#