Question

Find the number of atoms in 138 grams of nickel.

I'm not sure where to start. Can anyone help me?

Answer 1

Ni is about 68.7 grams per mol.
so
138/68.7 = 2.008 mol of Ni

that is
2.008 mol * 6.02*10^23 atoms/mol

= 12.1 *10^23 atoms

(quite a few )