This can easily be solved using dimensional analysis – find a way to cancel out units. Since each atom weighs 1.67 x10^-24 grams, it could be written as: (1.67x10^-24 grams/atom)
Therefore
Total mass in grams of all atoms = (7.05 x 10^ 23 atoms)(1.67x10^-24 grams/atom) = 1.1774 grams