How many atoms are in 58.93 grams of cobalt (Co) ?

If you have 58.93g of Co it means that you only have 1 mol (use a periodic table to find the answer, if you had more find it by proportion, it's easier).

There's 6.022 x 10^23 atoms per mol so you have 6.022 x 10^23 atoms of Co.

(once again if you had more mol, you could find the answer by proportions).